I would check your ALC setting when changing back and forth from each digital mode. You might need to readjust that setting. I run a little higher power on VarAC. So I have to readjust my ALC setting.
this is almost certainly a radio menu setting problem. if i screw up the settings on my ft991A i get exactly the same problem. the fact that it does not happen on ft8 means nothing. varac will require different settings.
the xcg author is very very helpful and will be sure to help you out.
I would check your ALC setting when changing back and forth from each digital mode. You might need to readjust that setting. I run a little higher power on VarAC. So I have to readjust my ALC setting.
Doug
KB8MRC
What soundcard are you using? I am using a DRA-100 with my 857d and have not had any issues.