I've had this happen several times, and it was always the position of the tank fill valve as mentioned above. I also had a 32 foot 2003 Brave. I also agree that you may have to purge the system of air.
The best point for me was the outside shower, since it has both a hot and cold valve and it won't fill the holding tank.. This will also allow your hot water tank to fill and push out the air. You might want to turn on the hot water valve at the outside shower and use the hose until you fill the hot water tank. You'll hear air until the tank fills and water comes out. Then, go inside and open each hot water valve at the bathroom sink, shower, and kitchen sink until water comes out. That should fill all of your hot water lines.
W8RLM - Bob
P.S. We loved the motorhome. We took it on the Winnebago caravan to Alaska. Had a blast.
2006 Winnebago Journey, Model 39K, 2013 Dodge Dart