Whenever I boot up a game my microphone is always greyed out despite being plugged into the PC and recognized by other apps, like discord. I have contacted support and they were not very helpful at all and offered no real advice on the topic. I am using an analog connection to my 3.5mm jack inputs so no USB connection is there to mess it up.

i have the same issue i talked to tech support a while back and they confirmed it is banned in my region , the game uses vivox for ingame comms and it turned out to be blocked in my region so check with your ISP or check if vivox is blocked in your region as well other than that , mic works fine in any other game even in insurgency 2014