Loopback - Old School Observation

When I set up my AXR 4 I set it up with the Digital B setting on AES/EBU and on my connected digital cable I connected the ins and out on the AES 7/8 pair together.
This enabled me to always have a loopback pair without needing the AX2TR driver swap on the Mac.

However I suddenly found nothing appeared on the AES 7/8 digital input despite the output receiving the signal correctly as show in the dspMixFx app.

This threw me for a while until I discovered that I had to change the AES/EBU Master pair to AES7/8 in the settings tab of dspMixFx. As soon as I did this the Mixer correctly displayed the input signal and loopback returned.

Anyone know why the software Clock Master pairing had to be set to the same channel as my hard wired I/o. As the Inputs and outputs were hardwired connected why did the mixer not show the input signal regardless of which pair were chosen as clock master?

Just can’t get my head round that. but the Loopback - old school works OK when that’s spotted.

I wonder if my initial setting got reinitialised after a reinstall as I had a problem with the latest dspMixFx duplicating it start up plists (install update not erasing old) .

Trouble with getting old you tend to forget what you’d set up a few months back lol.

If anyone can clarify the technicals re Master Clock setting here for me to aid my fading memory it would be appreciated.

My observations here may assist others who may be troubleshooting Loopback.