The video that OldBiscuit posted is EXACTLY what happened to me. Before I break camp I use an old ax handle to prop open the flush valve so the tank can fill. One time I got the handle down a little too far and it disengaged the piece mentioned in the video. Boy, was that an easy fix and a lesson learned.
2017 Toyota Tundra, Double Cab, 5.7L V8
2006 Airstream 25 FB SE
Equalizer Hitch