My mike periodically crashes in the S8+, I have to reboot it to re-active the microphone. Then it can work for a day or crash 2 hours later. What is going on and is it a known bug?
It just means when recording a message, it records zero sound.
Voice recording or call recording. Samsung is known to do all sorts of tricks to keep users from recording calls. (Although Call Recorder usually has at least one method that works.)
If it's voice recording, when it "crashes", does it work for phone calls? (If it does, it's a software problem with the recorder.)
If not, it could be a software or hardware problem. The fact that it "recovers" when you reboot would tend to indicate a problem in Android or Linux. (A reflash would fix that, but you can't reflash a Samsung without wiping all userdata, so you'd have to back everything up - and I mean everything - pictures, music, videos, apps you've installed, data [some of which you may not be able to get to], etc.)