Har kikat lite där men 2 saker fattar jag inte:
If you are running other software or hardware that can send MTC or MIDI clock, but intend for Logic to be the sync master, turn off Auto Sync In for Logic, to prevent Logic from receiving sync externally. The Auto Sync In setting can be accessed by click-holding the sync button on Logic's Transport.
If you are syncing Logic to another application or device via MTC, make sure that both Logic and the sync master are set to the same format. Make sure that Logic is not receiving both MIDI Clock and MTC. Also, configure the Audio Sync setting to "External or Free" in case the system is resolved to external Word Clock.