See this Comm Center post which is extremely detailed and has the solution.
So, the test for availability of offset tracking fails because tracking is off at that point, not because the mount doesn't support it. I don't know if failing the rate set when tracking off is new as of V5.05, or whenever, but I'd assume that all AP mount users would see the same problem, and possibly any others with similar behavior. (I think you fixed a similar problem in the X2 ASCOM driver due to TSX's similar behavior?)
Reopened for sequencing in ACP.exe during script rundown, also for AP driver.
Reopened again Feb 2015 for wind down with TheSky X after using track offsets.
