RtWysiwyg Edit Conflict Message

I just upgraded Xwiki from 9.8.3 to 10.11.2 LTS and also RtWysiwyg from some unknown version (probably around v1.28) to the most recent 1.34 release.

“Collaborative Editing” is not default for my user.

Whenever I try to edit any document, I get two warning messages on top of it, both basically stating that a concurrent editing session is in progress and I’m risking data loss, and one of the warning messages requesting me to enable Collaborative Editing.

If I do so by clicking the checkbox, the warning messages disappear.

There definitely is no concurrent editing session in progress and I’m the only logged in user, using only one browser window.

Uninstalling the RtWysiwyg plugin gets rid of both messages.

Any hints?

I added an issue for that in JIRA: