The fill line on mine dipped a good bit between the outside inlet and where the hose hooks to the tank. Water would pool in this area. I had to force water (seal around the hose where you stick it in the outside fill port) through the hose until it got flowing pretty good. Subsequently, Thor raised the hose to level during my factory visit last December and no issues since. Tech said it was a very common issue with a easy fix.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie