I can confirm that I have experienced also troubles with canceled calls from beginnen of the FP1, most likely due to bad reception ot the network (reason seems unclear…just by turning myself about 180° with the phone at my ear I can trigger a disconnection of an established call connection sometimes.)
I remember there are some forum topics, I guess it was still in the old forum, and will look up later for this.
The matter with the blackscreen from @andi_roe only happend once or twice…