Similar situation:
First, I have success when running mics in to my Focusrite 18i20, and USB out from the interface and in to my computer. DAWs recognize the interface, hear the signal, and sounds great when using Zoom.
But I want to add some effects to the signal. So after unsuccessfully trying to enter my HX Stomp in the mix described above, I tried this:
Mics go in to a simple 2-channel Mackie analog mixer (because the mics need power), main out to my HX Stomp, USB out of the Stomp and in to my computer. Again, any of my DAWs recognize the ASIO, and hear the signal (sounds great). Then I open Zoom...
Zoom recognizes the Stomp as an ASIO device, and shows up as a selectee in "microphones". But that's the end of it. Once I select it as my desired mic input, it won't work. Why, why, why???
Thanks,
Kirk