I experienced that MIDI Thru on MC8 is working fine in transparently sending back to the USB channel signals coming from my Strymon Timeline and BigSky (connected via DIN MIDI).
But my pedals Iridium and Sunset doesn’t do so. (They are set to the correct MIDI output mode, I checked positively with direct USB connection to the Iridium).
In the manual for MC8 “Cross MIDI Thru” explicitely mentioned the DIN MIDI only.
So is it “works as designed” and TRS is not (yet?) supported by this feature?
Firmware version is 3.7.2