Figured I'd add my extra experience here in case anyone reads:
From this thread where my mirror, horn, and parking sensors were not working.
https://www.1addicts.com/forums/show....php?t=1837178
Alright. Figured it out. Took it to the guy - he plugged in his computer. He said one of the buses was down.
I have one of the carplay/android-auto after market modules plugged in. He said, "it could be something there doing it. It says the whole bus is down. So, maybe one of the cables is loose."
Sure enough - I went and checked one of the fiber optic cables - wiggled it a bit and it came back... but then it also went away as soon as I didn't touch it at certain points.
How annoying.
So basically, something is either bad inside the cable itself (I certainly hope not! That would be a huge PITA to replace) or the module (maybe even worse to replace!). I will be investigating further when I have time but needless to say - it's the carplay/android auto module I installed from aliexpress and the connections used there.
Pro-tip for future folks.