I have small piers for a boat consisting of a square of about 5x5 blocks at water level. I have a 2-block gap for the boat to come in, picture the letter G and the boat enters the gap. A single is block just above water level at the entry point on the G, and I have a single trapdoor attached to that at water level. The idea is that when I come into port I open the trap door, sail in, close the trapdoor behind me, and when I get out of the boat it shouldn't go anywhere because of the surrounding blocks and trap door. To exit, I should be able to toggled the trapdoor open, exit, then close it behind me.
But it usually gets stuck in whatever position I last left it, and I can no longer open or close it. This happens with a couple trapdoors in the same configuration. On activation it toggles and then immediately re-sets. Might require game to be played for a while before conditions are set to cause this behavior. Doesn't seem to happen right after entry to game.
I'll provide more info as requested. I searched for open tickets for trapdoors but did not find anything that matches this description.