I just started having this problem this morning.
Ive recently been having trouble with clipping on my Kemper on clean profiles. I went into imput mode to see if I could address the problem. Both my clean and distortion sense are at 0. I tried turning the clean sense down a bit but it did not resolve the problem. About 30 minutes after that (clean sense at 0) the volume started dropping. I tried changing patches and the volume was still very low. I rebooted the system and it was back to normal for a short time then started dropping again.
ill be very interested to hear how this gets resolved.