KSATBob wrote on Sep 15^th, 2013 at 2:36am:

I have determined that the CTD is a result of improper AP settings. If you have the MOD SEL set to GPS you MUST have the switch set to NORMAL. If you have the MOD SEL set to GPS and the switch is set to HEADING, there is a good chance you may get a CTD. Also noted was that if you change these settings in the pop-up that does NOT mean that the settings in the cockpit (either 2D or VC) will reflect that change.

My 2D and VC A/P match each other. If I change anything on the 2D A/P it is copied in the VC, if I change anything on the VC A/P it is copied on the 2D A/P. Both of them move at the same time too (synchronized). I wonder why yours is different. :-/
Also. I always have the switch set to HEADING. I have never used it in the NORMAL position.