OK, I understand. I was simply grasping at straws. I cannot explain why your mount fails to actually move when told to do so, and yet it does not produce an error saying that it cannot move (and why not). And I assume you are 100% certain that the date and time are successfully pushed to the mount.

What happens if, at the beginning of the evening just before starting sky flats, you try to move the scope with the hand box or the "Slew/Sync" control on ACP? Do either work? DOes the mount refuse to move? Once you have done that, will it move in response to the Sky Flat commands? Again I am grasping at straws here.