I don't know for sure on that, it was just a possibility. Another thought just popped into my head as to erratic TSA functioning & that is if you've had the battery disconnected at some stage & you had to go back into the TFT & enable TSA, have you had to do this? If so, did you do the re-learn for the TSA?
It's a simple procedure of going through each gear for at least 10 seconds each. It was written in another post by someone else, I saved a copy. Try the below & see if it works or not. Each time I've done this the TSA works 100% right after the last 10 seconds in 6th.
