I never use the pull dump. It wasn't taught to me, so I was never tempted.
The only time that I have had something similar happen was in the pool with my wings. I was doing skills practice for my Advanced Nitrox course. I had taken off the power inflator for some reason and didn't believe the other divers when I was told that the gasket for the power inflator was a real witch to line back up correctly. I had done it many times on ProQD+ after all.
I jump in and my buoyancy is terrible. I would add air, go back up, then sink. After inflating my drysuit to bring me up and going to the shallow end, I checked for my air leak. Sure enough, I hadn't seated that gasket properly on my wings. I was blowing air out of that gasket. Needless to say, I avoid pulling that power inflator off now. And when I do it again, I will check for air leaks much more carefully because that gasket doesn't seat as nicely as the one on my other BC (and I am paranoid about that one after I pull the Airsource off for maintenance as well now).