Describe the bug
When adding tags into the box, they appear, then randomly disappear from the box. They don't save unless they then reappear. Which has happened on occasion.
There's also no frequently used tags option which was vital to my work in the classic editor.
Using latest Gutenberg Version

To Reproduce
Steps to reproduce the behavior:

1. Go to 'New Post'
2. Click on 'Tags box, write in a tag and use either a comma or enter to add the tag'
3. Tag(s) will disappear. Sometimes will reappear with no consistency or pattern.
4. Most recent article I wrote was about subculture aesthetics in The Flash tv series. I used at least 10 tags which were previously unused, so had to be manually input. It only registered one.
5. I can go into All Posts, select my article and use the Quick Edit to add tags. But I shouldn't have to.

Expected behavior
When tags are entered they should be saved to the post and not simply disappear.
Frequently Used tags would be extremely beneficial to the system.

Screenshots
Sadly this is not something I can screenshot and don't have a video screen capture.

Desktop (please complete the following information):

• OS: Windows 10
• Browser Chrome
• Version Up to date

Additional context

• Please add the version of Gutenberg you are using in the description.
• To report a security issue, please visit the WordPress HackerOne program: https://hackerone.com/wordpress.