Here’s a report from @Robr in this February 2020 post:
She [the doctor reviewing x-rays] was stunned by the results and was wondering why it’s on the inside of my arm. THE SENSOR WIRE MIGRATED.
I know this is anecdotal but I’ve read similar accounts over the years. This is likely a rare event, not one that could be used for a scientific trial, if there were ever any financing for this kind of study.