This is how I experience it. At random moments TA fails and, if it was engaged, it gets knocked out. But I may re-engage it right away and it will continue working until next failure. It is not common for it to fail for long time continuously, when yellow lights are staying lit on dashboard, however, it may happen, and then I couldn't engage it. 1896 as well.
By the way, I'm getting sometimes OTA updates. There is never ever any info about what updates are including and whenever they are installed, the page with the list of updates (when checking in system info) stays blank. However, some changes happen. For example, once I got a feeling that my car had auto hold function when I was buying it, but it didn't work and I couldn't find it anywhere in the settings. When I realized that, I just shrugged and thought it is just another feature which disappeared after my dealer changed entertainment module and upgraded software after my first visit to a workshop. But recently, after another OTA update, auto hold just appeared and working fine like it is supposed to... Go figure what surprises I should expect with next updates.