Been Using ACR for a while now and never had any problems but recently it has started to not record calls sometimes for no reason. It shows that its recording makes a file but leaves it empty. I used to rely on it for a backup in case I forget things as I am on the road a lot. Resetting the phone fixes the issue and it starts recording again but this is not reliable.
ACR 16.5 Galaxy S6 - SM-G920F Android 5.1.1