I put in a new ticket, I'm updating based on information I've discovered. At this point I KNOW I've done significantly more hours of troubleshooting than Tesla has.
There was a person at the service center, who did (on my requirement, but was also willing) took a good 30 min to review the issue, see it in person, and hands on. I thought we had a good conversation, and hopefully it will be fruitful.
If I had to guess, he's being given incorrect information, but states he will continue to advocate for me.
Because the app is only on my phone, and I'm not 12, I'll be writing the issue here for all to see then copy/pasta into the app.
ISSUE:
For over 6 months, and since an update near that time-frame, XM behaves as if it 'forgets' the XM radio presets. (they still show on the screen as existing). If you favorite multiple stations, the 'next' and 'back' buttons on the steering wheel operate 100% correctly, just as page 46 of the owners manual:
https://www.tesla.com/sites/default/files/pdfs/JO/model_x_eu_en.PDF state. After approx. 20-30 minutes, the vehicle 'forgets' that the XM presets exist, and the 'next' and 'back' buttons on the wheel operate XM stations incrementally. 1,2,3,4,5, etc. Rather than moving soley between saved presets. If you remove and re-add presets, it operates correctly again. The 20-30 minute 'forgetting' occurs whether the car is in operation, or parked with no one in it. This is reproducible on demand as well. Setting favorites, maneuvering through them correctly. Then within 20-30 min, the car 'forgets' they exist, and operates accordingly. Every time, without fail.
At this point, I know when it occurs. I know how it occurs, and I can replicate it on demand. It worked (failed?) so perfectly within the 20-30 min mark, that when the sales person and I were sitting in the car, it worked correctly for him, for about 5 min, then without even putting the car in drive, failed perfectly!
I even know where it occurs - software. Something is "forgetting" the favorites exist, and I'd even fix it for them, if I had access to the source code, or could remote into a machine that did. I'd happily take my time to fix it. Anything is better than being gaslit about an 'algorithm' controlling presets.