It turns out if you equip a riot shield and go riht up to a wall, all you need to do is to press on R1 the square button, and L1. If you tap those rapidly, you can solidly pass through walls.
Here is an example: if you are playing airport in co-op arena, go to the planes and at the back end of the warehouse bulding. Rapidly press the combo, and the is a whole area behind the building for refuge.
If you got any other gitches put em here with your experience withit.
There are plenty of glitches in all modes but I wouldn’t suggest posting any. Normally, I’d suggest sending them directly to ND but at this point, I doubt they’re going to address them.
What you described isn't an Co-op exclusive glitch.
The Riot Shield one is. The animation changes in other modes.
I can do the riot shield glitch on Airport & Desert Village in Comp.