Your summer pump (loop 1) may have failed. To test, turn the bypass switch to on and run the burner. This will run the heated fluid through all zones. If you get, and keep, hot water, chances are the pump is bad.
The bypass switch can be found on the top of the silver box next to the Oasis. Sorry this photo is showing sideways.
Close up of the switch:
If the bypass switch solves the problem, you can turn it on when you want hot water and then turn it off when done or it will heat up your coach.
Either way, a call to ITR (Oasis) on Monday is in order. They can walk you through testing the heater and help diagnose the problem, and they can send you a replacement pump, if needed.
I suggest you post your coach model and year, so folks would know whether or not they can help out.