This has been happening to me since I got the FP2 in early January. At first I didn’t consider it too important but it is bothering me more and more.
It appears that during a call, if I change screen (opening another app or even the contact list!), whether by accident or on purpose, my microphone mutes. It is extremely annoying when it happens to be my ear touching the screen by accident and suddenly the other person cannot hear me and I have to quickly switch back to the call screen before they hang up.
Anyone experiencing this same problem? Is there a way to change the settings so this doesn’t happen?