OK! So my Model 12 is connected via USB to a Mac running Harrison Mixbus. The Model 12 MIDI Out goes to a MIDI patchbay to clock other gear. In this mode the Model 12 is an interface, with recording and playback tasked to the DAW.
The problem was when using the DAW to output MIDI clock, I wasn't getting clock through the Model 12 to the external hardware. Notes were coming through, but no clock.
I spent a long time checking and re-checking Audio/MIDI Setup settings, the interconnections within the DAW, and all the options on the Tascam.
The solution was that Mixbus has a setting under Mixbus Preferences > Transport > Generate that allows the user to turn on/off the generation of MIDI clock, amongst other things. Enable that, sorted.
For reference, the various options for sending timecode, control, and clock during playback/recording are outlined on page 688 of the current Mixbus User Manual (Dec 25).
The Tascam passes these sync messages through to its MDI Out.
