I too have fallen foul of the Build Authorisation.
I purchased TRS22 Platinum as a standalone product last year, its cam with 12m HD terrain trial, I was advised that the trial had expired but not than my authorisation would be locked.
I have logged a ticket and waiting fingers crossed.
One thing I noted was the splash screen on loading, although my purchase was Trainz 22 Platinum, the splash screen has always shown Trainz+. Does this mean anything, do I need to reinstall Trains 22 Platinum?