I can't believe the sus pedal has anything to do with it because if I change voices outside the grand piano settings with the sus pedal depressed it works fine. Or if I change voices within the bank of 4 grand piano settings with the sus pedal depressed it still works fine. The sound interruption only occurs when changing voice selections into or out of the grand piano selections.
I agree it probably needs to be something addressed by Yamaha but I haven't been able to find a way to get them to respond to me. The dealer has backed away and my email attempt has been ignored. I was told there is a 5 year warranty on the unit when I bought it. I have to confess I'm not impressed with their service.
Contact your state Attourney General as this is a breach of state law concerening Warranty of your product sold in State of XX you paid well over a thousand dollars for the unit and you deserve some satisfaction