Go to Options, Project, Clock, set source to SMPTE/MTC.
Then go to Midi Out, checkmark Transmit MMC.
This will cause the MTPAV to generate timecode. The Adats and Cakewalk/Sonar will sync to the MTPAV.
If this still does not work, try hard resetting your MTPAV by turning it off and holding PANIC for a few seconds while powering the unit on. The default setup will generate timecode.