If anyone still isn't aware, the Steering Assist failure problem was a by-product of 17.42 (like the SAS alerts), and I had it a few hours after installing the firmware Saturday morning. I restarted the car (powered down, waited four minutes, started it), and it was cleared. It's been fine ever since. After checking with the Diagnostics team, Fremont said it was the software trying to find parts that aren't there. (Literally) Perhaps a chunk of code not meant for AP2.5 cars was left behind? 17.42 has been pulled and looks like new 17.42.1 coming today may be the fix.
As usual, TMC sounds like a disaster, but as Bonnie says, her (older) X is fine, and that's usually the case. Problems get brought up here but there are thousands of happy users that aren't on here (or never heard of TMC).
However, for those that are, I would advise people to be aware of how to totally restart their car and have a mobile app ready to start it back up in case the brake pedal doesn't work. That's what I had to do, and that is a lot better option that waiting hours for Roadside to get back to you or waiting for a flatbed that you actually do not need (in this case).
It looked like Roadside was so busy between the usual weekend issues and from 17.42 that it took them six hours to get back to me; I wasn't stuck on the side of the road, however, and they did know that.
