FP3 - Poineer AVIC - Synchronization of the phones call list lost

I don’t know what I did, but suddenly the synchronization of the call list of my FP3 and my Pioneer AVIC got lost.

I have now reset the FP3 several times. After that everything is going great. But then after some change the problem occurs again.

Does anyone here have any ideas?
I’m going to test the synchronization after every change - maybe I’ll find the cause this way.

Thank you!