"Edit Conflict" Warning is Always Displayed

(Actually observed in version 1.34, but unfortunately I cannot select this version here in JIRA.)

I just upgraded Xwiki from 9.8.3 to 10.11.2 LTS and also RtWysiwyg from some unknown version (probably around v1.27/1.28) to the most recent 1.34 release.

The “Collaborative Editing” setting is disabled by 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. One of those warning messages requests 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.

Am I doing something wrong, or how can I fix / work around those misleading / wrong messages?

Maybe those wrong messages are related to RTWYSIWYG-76?