As far as I can tell, the ink contains iron oxide which conducts and heats when the RF is applied.
The person we scanned had too much pain for us to continue. The tattoo was not new. I recall another similar incident too. I also have a colleague who scanned someone with recently tattooed eyebrows and the MR caused very significant pain.
The problem would seem to be under reported (see links below which make it seem fairly rare). That said, we don’t have anyone we would report it to and rely on techs talking to each other and sharing these things - which happens regularly.
New risks are discovered fairly regularly. In recent memory: smart rings, squirreled away blood sugar monitors, penile implants, penile beads, hair extensions that are attached with wire. A low level of trust is key.
