Hello,
Are you using the pedal or H90 Control to save your Program when this happens?
I just tested this using a MIDI monitor app. When saving using the pedal, the only MIDI message I am seeing when a Program is saved is the MIDI PC message for the Program that is being saved (example: save Program 40 and it sends MIDI PC 40). When saving using H90 Control, there is some additional SySex data being sent, perhaps this could be causing the issue with your amp switcher.
If you are using H90 Control to save the Program, can you please try saving using the pedal (press and hold the Programs button) and letting me know if the issue still happens?
