GRAV Admin Cache Issue

In my multi language GRAV site I recently noticed a cache issue.
When I change the language in page overview I get the message Successfully switched language and anything seems alright.
But when I edit a page and go back to the page overview, the original language appears again instead of the recently selected language, furthermore i get the message invalid security token.
Only if I force a reload without cache the selected language appears correctly and the message disappears.
On the next language change the issue occurs again.

How can I solve this issue ?
Thanks in advance

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