USB Thru from iPad to MC6 to Boss RC-600 (or any other device)

Hi, I would like to connect my iPad the my MC6 and sent a CC TEMPO message for my RC-600(which in effect will change tempo on my HX-Stomp also). for some reason I cannot pass the message through the MC6 - If I connect the USB Cable to the RC-600 Direct it works - what parameters do I need to adjust ? Am I doing something wrong? I started this journey as Level 0 Midiot I would class myself in level 1 now with a long journey ahead of me. any help would be appreciated.

On the MC6 you’ll just need to enable Cross MIDI Thru in the Controller settings so it will pass incoming USB MIDI messages out to DIN and vice versa