Hey I just have to ask - don't you check the wing before getting in? Inflate, dump via the deflate, button. Inflate, dump via a dump valve. Inflate, dump via the other valve...
Btw, a buddy went through the same ordeal that you described. I saw the events unfold and it was somewhat comical to watch. I bet my friend will disagree.
For sure all the pre in the water and once in the water checks for both dives nothing evident.
Like I said 20 mins into the 1st dive go to dump air the entire dump comes off in my hand.
Exit, no big deal fairly flat profile just have to switch to a more heads up trim.
2nd time more of an up and down profile so a lot more challenging.
2 jumps and a T in I thumbed it, had to disconnect my LPI hose and hand off my stage to buddy.
Whatever air i put in the wing was migrating to the left side and rolling me to the right, ended up finishing the dive trying to trap air in my right arm while holding it out to the side to compensate.
Not fun, 1st time in 23/24 years of cave diving I felt the need to stop while exiting and take a lets go with take a few mental sanity breaks.
Upon surfacing it became obvious that the wing was continuing to adding air after every time I did.
Everyone preaches your DS is your back up buoyancy, 1st time I've ever had to, not fun, just my thoughts but this should be a requirement in training.