Hi,

unfortunately the only thing that helped me out was the stupid thing to reset my phone. I checked a lot of things and also the suspicion that a particular app or tool I installed might have caused the problem. But meanwhile I have "manually restored" the old state and bunch of apps I also had before and the problem did not show up again.

So, would be cool to know at least afterwards what was the problem, so anyone having an idea or a hint is highly welcome ;-)

Good luck and best regards.