Train arrivals flashing with arriving train

I have a station that is supposed to be getting filled with water but the train arrival just keeps flashing with a train saying its arriving and then disappearing. This is very confusing and I feel like shouldn't be happening. Attached is a vid of it happening and a save shortly after the vid. I have also encountered this with several other stations.

I would expect that is a train is assigned to that station it should stay assigned to that station.