I have a West Oil stop where I want the train to fill up on oil. I also have an East Oil stop, where I want the train to unload. These stops are connected by a simple figure eight track with no signals, and I can manually drive it between both stops without issue. For some reason my wait conditions work when I don't want them to, and don't when I do.

I want the train to stop at the West stop when it is empty, and stop at the East stop when it is full.
Instead, when the train is full (25k capacity), it will stop at the West oil, but not stop at East.
What am I doing wrong here? Am I completely misunderstanding the logic used?