2008 X3 3.0si TPM error - more tire pressure issues

My X3 has been pretty reliable since I had the warning light problem when I first purchased it. I believe once or twice I reset the tire pressure monitor (TPS) system just to do it in the last several months. Maybe once I saw the yellow icon error message, but I believe it went away on it's own or after topping off the pressures. I had not observed any major issues in the system since owning the car.

I had a 2" hitch installed at Rack & Road (it looks pretty good, I can share photos) today, and now the TPS is signaling a system malfunction. The light will stay on solid while driving and will flash sometimes too. The instructions say this is a system malfunction and I might have to get the system serviced. I tried holding the TPS button for 5 seconds but the icon comes back immediately. Tires are filled to 46 lbs (including the spare but I read the spare has no TPS monitor) but the error persists. I'll check the pressures again tomorrow and will try more resets. Has anyone seen this issue before? My X3 has backup sensors and I did get the wiring harness installed so I'm concerned something screwy happened during the integration process.

I'll post more tomorrow, let me know if anyone's heard of this and if there's a fix!

Best, Chris