If you send a Sync into TheSky with a TPOINT model active, apparently it causes an error to come back to ACP. Are you certain that you don't have TPOINT active somehow? If TPOINT is not active, then this is a bug in TheSky:

"Calling Telescope.Sync() through the ASCOM interface causes an error to be raised"

You'll have to work this one through Software Bisque. I will be happy to help them as needed with info, however it's quite simple. And if this has been working prior to your update of TheSky, it should be straightforward for them to find where the issue was introduced. This sort of thing happens to all of us software developers, all we need is to know about it so we can make it right.