Thanks for the video, but I'd already looked at it and while it has a nice close up of the bypass valve, it doesn't show where that compartment is located. Is it by chance behind the bedroom drawer on the passenger side? That location would be proximate to the water heater.
P.S. This is RV #3 for me and I've never had an mystery experience like this.
Well, I finally found it! It was located (logically) behind the lower left side bedroom drawer. That location is actually behind the heater. BTW it wouldn't have hurt for the manufacturer to have put that in the owners manual. On that point I have to say my twenty year old Winnebago Adventurer beat my current ride hands down.