Issue with translation - language not allowed


I got a strange issue concerning the language. My backenduser (non admin) is limited to english and french, the page is translated and basically everything works fine.

But: if the user tries to edit the root page of the page, he receives the following error when editing the english part, which is the main language:

recordEditAccessInternals() check failed. [ERROR: Language was not allowed.]

The changes however are taken into account, but the red warning that appears with error above is annoying. The error doeas not appear on the subpages.

Anyone a clue? Using Typo3 10.4.23