I just tried running a session on the C&O Hinton, specifically the coal drag session. It uses the 2-6-6-6 loco.

I get about 5 miles from my starting point and I'm showing zero water in the tender, the boiler pressure drops to zero, and the train stops, as it should.. If I Ctrl-right click on the tender it shows that I have 92542 for the water amount.

Had the same thing happen when running one of Phin Skene's model railroad activities. What's going on?