Cubase 9.5 will not read MTC

Hi all… I have a peculiar anomaly that can probably solved very easily, only I’m probably being really stupid.

I have 2 macbooks, both running Cubase 9.5, one is my main audio computer, running a UR824 into an 01V96. The other is my secondary computer, running a Behringer FCA610.

I have a 4 way MIDI out box connected by USB to the main macbook. Work perfectly for every other device. The output of Port 4 goes to the input of the FCA610. I send MIDI notes and information down that line, and the second computer receives it in Cubase.

However, what the second version of Cubase will not do is sync to the master version under any circumstances whatsoever.

I set the slave to receive MTC from the FCA 610, and set the ‘Use External Synchronisation’ to active. I set the master to output MTC to MIDI Port 4. Nada. Receives nothing.

If I then launch Reason on computer 2, without it rewired into cubase, it will receive MIDI Clock, and generally behave as expected.

Any help gratefully received, cheers!