Steps to reproduce the issue

Joomla 4 beta 6 admin console.

Set Default Editor to CodeMirror

Edit an article - save it.
Click Publishing tab.
Click Save and close.
Click article name to edit it again
Note that we (correctly) are on the Publishing tab
Click content tab

Note:

• No line numbers
• no text

Click into the content area
Note:

• Line numbers now show
• Truncated content now shows

Click refresh (browser window) (or as in video below, Save, to refresh the page and have it load with the content tab active)
Note: Article text loads as expected

This effects the frontend too.

Expected result

as above

Actual result

System information (as much as possible)

Safari on macOs

Additional comments