Hey I found your post following the same problem I had with another game. I found that I was using Logitech's G HUB which was changing the Profile to the game and setting the gain extremely low. Figured it might be the same issue you had even though it was almost 2 years ago now and maybe others will run into this post looking for answers.
Made an account to say than you very much...this was exactly my problem..apex was cutting my mic in half and it turned out g hub was auto switching it to an apex profile where the gain was really low..played with it and got it back to normal! So Thank you very much!
