Following.
I'm having similar problems with my Stomp. I use the FX loop for wet effects at the very end of my chain. Whenever I put a stereo FX loop at the end of any of my patches the entire rig sounds plasticky like a toy. Even when all the pedals are in bypass.
My set up is Guitar to Stomp: comp, drive, cab, IR, then FX loop: mono to AlterEgox4, mono to Polymoon, stereo to Bigsky, stereo to Beatbuddy, stereo back into Stomp.
I wasn't having this problem before. Could it be from 2.8??
Cheers,
John.