have a similsr problem on a friends 520.he has 2 weeks off and sat nav wont do the truck thing,,,,,,,,i have tested it i.e 1 week on 1 week off and it's fine..he swears he dont do anything else.
maybe a problem with certain units as in a "friday build"

I just get the legal notice when I press reset. I do not get the vehicle selection option. I only receive the option randomly.

I just tested it and it really seems to get to stuck in that setting, even with the original NC (patched only).
One thing I found out that always gave it back (6 tries) was removing the SD and to start from the internal (9.430).
Next start with the SD back I got the vehicle selection at startup.
Last try:
Create a textfile with a number between 20 and 30 in it.
Save as "suicide.dat" in the root of the Truck NC.
When you press the power next time to turn off the TT will onl go into sleep mode for time in seconds you specified in the suicide.dat, after that the device shuts fully off.
Check if that brings you back the vehicle selection.

Didn't seem to make any difference starts up as normal. Something strange has happened tom-tom services has disappeared in preferences been replaced by Tom Tom traffic. I put Switch file "bton" in "config" folder as that seems to work on my tomtom car navecore 8.562 makes services available in preferences.

I have noticed when I enable "show fewer menu options" TomTom services becomes available. Does anyone know why this may be happening and if I would be able to make TomTom services available without having to enable "show fewer menu options?"