hmm… probably depends on what kind of sound you route through…

If you have a pad and you fiddle around with the comp attack, then that won’t do much. But on drums, the comp should be audible in any case.
For a test, lower the treshold to close to 0 and crank up the ratio. If you don’t hear anything then, the problem is not the comp.

I use the comp on the master track to tighten the mix, albeit only at a comp-dry mix ratio of roughly 60-40