How long have you had the xM1 installed? P5 has pretty thick skin, so I wouldn’t be surprised if that plus just even a little bit of swelling would get in the way of a good read.
If you can successfully get a hf mf info, it will confirm for sure what your xM1’s Magic capabilities are.
I’m sure you know that the orientation of the antenna should be perpenicular to the lengthwise orientation of the implant, such that they make a “t” or an “x”? I just want to confirm.