Can you route 1-2 to patchbay? eg via Presonus Quantum

[tj7]

Howdy -

Presonus Quantum / Samson Patchbay / PT Studio 2023 / iMac Pro

Potentially the answer is staring me in the face but I'm still missing it!
I have all 8x channels routed to and from my patchbay. Works like a dream.
However.
I am running a mic into mic input #2 via the front of the Presonus (which has 2 mic inputs there). I'm getting a signal and tracking dry it's working just fine.

Using my trusty patchbay I am trying to route that channel #2 OUT to a rack compressor and then from that compressor to input #6 for my compressed signal. This sort of thing I do routinely from inputs 3-8, but there is something tricky about the process when it comes to 1-2 because I know this is also where monitoring happens. This is where my brain starts to melt.

I'm getting absolutely no signal from #2 to my compressor, even though I have absolutely got it patched from #2 to compressor. I have checked that my patch cable is not faulty. I have checked that a plain signal to #2 is happening (ie when there is no patching), and it is fine. Yet when I patch out from that channel to my compressor, zero signal.

I assumed that ultimately ALL channels can be patched etc in the same way, but evidently not with 1-2. Am I correct about this? What am I missing?

Any help would be much appreciated!

Thanks