Notes just deleted an important document via "undo"

[illnesse]

I'm on latest RC. My notes folder is pointing to a directory with documents on an external storage . I opened a document via Notes app and was wondering why the undo arrow icon was highlighted, i thought maybe i pressed a key by accident and added a character somewhere, so i presssed the undo button, which cleared the entire content and there is no option to "redo".

This seems to be a visual bug in the Rich Text Editor only, if i switch to normal edit or preview mode, the content of the file is back. Switching back to rich text, the file is empty again.

Steps to reproduce

1. Open existing document in rich text editor
2. Press Undo button (which shouldn't be active since there were no changes in the first place)
3. Lose entire content, editor window is empty with no possibility to restore content

Button shouldn't be active, or at least give possibility to redo

[DemoFreak]

I just had the same problem with version 4.9.0

I use the rich text editor.
When opening some notes, the undo button was active and the indicator for unsaved changes was visible.

When clicking on Undo, the entire content of the note was deleted, Redo is not possible. The content of the file in the notes folder was also deleted.

The problem cannot be reproduced or I have not yet found a way to do so. The problem only occurs with some of the notes, and if you open another note directly and then return to the affected note, the problem no longer exists there (undo button inactive, no unsaved changes). All you have to do is leave the unsaved note and open it again directly. The modification time is not changed, so it is obviously not really saved.

[DemoFreak]

I have just restored the file from a backup.

The content of the note was then displayed again, but still with the modification time from when the content was accidentally deleted using the undo button.

After "occ files:scan" the preview and the modification date of the md file in the Notes folder was correct again, in the Notes app the warning was displayed that the file was changed externally (only now after "occ files:scan").
After selecting one of the two possible variants, the undo button became active again and the notice on unsaved changes was displayed.
Simply closing and reloading the note (see above) again fixes the problem, Undo is inactive and there are no unsaved changes anymore, the modification date is displayed as original again.