I just realized something else. I'm using the Kemper's stereo out (XLR main) to two channels of the X32. However, I'm using the P1 monitor amplifier with only one XLR and mono. Could this be the problem?
Try muting one of the channels your kemper is plugged into. If it sounds good (but only one side), then yes - what might be happening is the X32 is summing the L&R channels on your bus out to your P1, and that's causing a cancellation effect. If this is the case, check the POLARITY on one of the channels. I've not powered up my X32 since before COVID so I can't remember where that is on it- sorry, but you should be able to find that pretty easily.