Description

The customize widgets editor disappears leaving only a grey panel when selecting some blocks (paragraph works ok, blocks like image or latest posts cause an issue)

Step-by-step reproduction instructions

1. Activate a classic theme like Twenty Twenty One
2. Go to Customize > Widgets
3. Select a non-paragraph block

Expected:
The block is selected and is still visible:

Actual:
The editor disappears like this:

Or maybe more like this:

Screenshots, screen recording, code snippet

No response

Environment info

It seems to only happen with the Gutenberg plugin active. It's ok when I check WP6.6

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes