Quick summary

When saving a template in the site editor, the content is erased in the background on save.

After the save a “select a pattern” modal is displayed. If I close that modal, all of my content remains visible in the editor, but I get an Empty template: error on the front end. Refreshing the browser shows the empty template.

Revisions show the template was saved blank and all content was removed.

Steps to reproduce

1. Edit a template in the site editor.
2. Save changes.

What you expected to happen

The template to be saved with recent edits.

What actually happened

All edits are removed and the template is saved empty.

Impact

One

Available workarounds?

No and the platform is unusable

If the above answer is "Yes...", outline the workaround.

If the content is copied from the site editor's code view before refreshing it can be restored manually. If not, the best approach is to restore the revision that preceeds the blank save, though it will be missing edits made between it and the save that wiped the content.

Platform (Simple and/or Atomic)

Atomic

Logs or notes

The issue does not occur on every save, so it's difficult to replicate, but I have experienced it on two separate WPcom Atomic sites. We've not been able to replicate on a self-hosted site.

Slack discussion:
p1723075356929419-slack-C01M1J49Q75