[Rich Breen]

Everyone so far is pointing to I/O or inactive faders, but the OP is saying though that the faders have *active* inputs and outputs and are functional and passing audio, so it's not an I/O issue. I'm curious if the faders behave normally WRT automation? Also curious if there's a control surface involved?

I've never seen this, and can't really imagine what it could be if in fact faders are fully functional, passing audio, automating, etc.