backup:run says it's successful; no data actually written

[nexxai]

Ok I've probably just messed up a setting, but I'm trying to get laravel-backup setup with Spatie's flysystem-dropbox filesystem adapter and I can't seem to get it to actually write data.

When I run backup:run I get this:

Starting backup...
Dumping database fortunavista...
Determining files to backup...
Zipping 3029 files and directories...
Created zip containing 3029 files and directories. Size is 279.72 MB
Copying zip to disk named dropbox...
Successfully copied zip to disk named dropbox.
Backup completed!

but the email confirmation I receive after it completes (which incidentally takes about the amount of time it should take to upload that amount of data) says:

Hello!

Great news, a new backup of MY SITE was successfully created on the disk named dropbox.

Application name: MY SITE

Backup name: MY-SITE

Disk: dropbox

Newest backup size: No backups were made yet

Total storage used: 0 B

Newest backup date: No backups were made yet

Oldest backup date: No backups were made yet

Regards,
MY SITE

which is confirmed when I look in the folder for the DropBox "App" I created; there are no files there.

Here is my backup.php in case it helps:

<?php

return [

    'backup' => [

        /*
         * The name of this application. You can use this name to monitor
         * the backups.
         */
        'name' => env('APP_NAME', 'laravel-backup'),

        'source' => [

            'files' => [

                /*
                 * The list of directories and files that will be included in the backup.
                 */
                'include' => [
                    base_path(),
                ],

                /*
                 * These directories and files will be excluded from the backup.
                 *
                 * Directories used by the backup process will automatically be excluded.
                 */
                'exclude' => [
                    base_path('vendor'),
                    base_path('node_modules'),
                ],

                /*
                 * Determines if symlinks should be followed.
                 */
                'follow_links' => false,

                /*
                 * Determines if it should avoid unreadable folders.
                 */
                'ignore_unreadable_directories' => false,
            ],

            /*
             * The names of the connections to the databases that should be backed up
             * MySQL, PostgreSQL, SQLite and Mongo databases are supported.
             *
             * The content of the database dump may be customized for each connection
             * by adding a 'dump' key to the connection settings in config/database.php.
             * E.g.
             * 'mysql' => [
             *       ...
             *      'dump' => [
             *           'excludeTables' => [
             *                'table_to_exclude_from_backup',
             *                'another_table_to_exclude'
             *            ]
             *       ],
             * ],
             *
             * If you are using only InnoDB tables on a MySQL server, you can
             * also supply the useSingleTransaction option to avoid table locking.
             *
             * E.g.
             * 'mysql' => [
             *       ...
             *      'dump' => [
             *           'useSingleTransaction' => true,
             *       ],
             * ],
             *
             * For a complete list of available customization options, see https://github.com/spatie/db-dumper
             */
            'databases' => [
                'mysql',
            ],
        ],

        /*
         * The database dump can be compressed to decrease diskspace usage.
         *
         * Out of the box Laravel-backup supplies
         * Spatie\DbDumper\Compressors\GzipCompressor::class.
         *
         * You can also create custom compressor. More info on that here:
         * https://github.com/spatie/db-dumper#using-compression
         *
         * If you do not want any compressor at all, set it to null.
         */
        'database_dump_compressor' => Spatie\DbDumper\Compressors\GzipCompressor::class,

        'destination' => [

            /*
             * The filename prefix used for the backup zip file.
             */
            'filename_prefix' => '',

            /*
             * The disk names on which the backups will be stored.
             */
            'disks' => [
                'dropbox',
            ],
        ],

        /*
         * The directory where the temporary files will be stored.
         */
        'temporary_directory' => storage_path('app/backup-temp'),
    ],

    /*
     * You can get notified when specific events occur. Out of the box you can use 'mail' and 'slack'.
     * For Slack you need to install guzzlehttp/guzzle and laravel/slack-notification-channel.
     *
     * You can also use your own notification classes, just make sure the class is named after one of
     * the `Spatie\Backup\Events` classes.
     */
    'notifications' => [

        'notifications' => [
            \Spatie\Backup\Notifications\Notifications\BackupHasFailed::class => ['mail'],
            \Spatie\Backup\Notifications\Notifications\UnhealthyBackupWasFound::class => ['mail'],
            \Spatie\Backup\Notifications\Notifications\CleanupHasFailed::class => ['mail'],
            \Spatie\Backup\Notifications\Notifications\BackupWasSuccessful::class => ['mail'],
            \Spatie\Backup\Notifications\Notifications\HealthyBackupWasFound::class => ['mail'],
            \Spatie\Backup\Notifications\Notifications\CleanupWasSuccessful::class => ['mail'],
        ],

        /*
         * Here you can specify the notifiable to which the notifications should be sent. The default
         * notifiable will use the variables specified in this config file.
         */
        'notifiable' => \Spatie\Backup\Notifications\Notifiable::class,

        'mail' => [
            'to' => 'nexxai@gmail.com',

            'from' => [
                'address' => 'nexxai@gmail.com',
                'name' => 'Fortuna Vista - Backup',
            ],
        ],

        'slack' => [
            'webhook_url' => '',

            /*
             * If this is set to null the default channel of the webhook will be used.
             */
            'channel' => null,

            'username' => null,

            'icon' => null,

        ],
    ],

    /*
     * Here you can specify which backups should be monitored.
     * If a backup does not meet the specified requirements the
     * UnHealthyBackupWasFound event will be fired.
     */
    'monitor_backups' => [
        [
            'name' => env('APP_NAME', 'laravel-backup'),
            'disks' => ['local'],
            'health_checks' => [
                \Spatie\Backup\Tasks\Monitor\HealthChecks\MaximumAgeInDays::class => 1,
                \Spatie\Backup\Tasks\Monitor\HealthChecks\MaximumStorageInMegabytes::class => 5000,
            ],
        ],

        /*
        [
            'name' => 'name of the second app',
            'disks' => ['local', 's3'],
            'health_checks' => [
                \Spatie\Backup\Tasks\Monitor\HealthChecks\MaximumAgeInDays::class => 1,
                \Spatie\Backup\Tasks\Monitor\HealthChecks\MaximumStorageInMegabytes::class => 5000,
            ],
        ],
        */
    ],

    'cleanup' => [
        /*
         * The strategy that will be used to cleanup old backups. The default strategy
         * will keep all backups for a certain amount of days. After that period only
         * a daily backup will be kept. After that period only weekly backups will
         * be kept and so on.
         *
         * No matter how you configure it the default strategy will never
         * delete the newest backup.
         */
        'strategy' => \Spatie\Backup\Tasks\Cleanup\Strategies\DefaultStrategy::class,

        'default_strategy' => [

            /*
             * The number of days for which backups must be kept.
             */
            'keep_all_backups_for_days' => 30,

            /*
             * The number of days for which daily backups must be kept.
             */
            'keep_daily_backups_for_days' => 30,

            /*
             * The number of weeks for which one weekly backup must be kept.
             */
            'keep_weekly_backups_for_weeks' => 1,

            /*
             * The number of months for which one monthly backup must be kept.
             */
            'keep_monthly_backups_for_months' => 1,

            /*
             * The number of years for which one yearly backup must be kept.
             */
            'keep_yearly_backups_for_years' => 1,

            /*
             * After cleaning up the backups remove the oldest backup until
             * this amount of megabytes has been reached.
             */
            'delete_oldest_backups_when_using_more_megabytes_than' => 5000,
        ],
    ],

];

Can anyone point me in the right direction?

[nexxai]

After some more trial and error on my test machine, I just tried removing all the media (as a test; in production I require this media to be included in the backup) and with a backup size of ~10MB, it actually worked as expected, which makes me wonder if something is silently timing out during the upload of the larger file.