For the last 3 Year I have had my Lift3 and I have had this vacuum problem from day one. I do not know why but after a ride my Deck lid can not be opened because it has sucked it self to the board and deck seal. Some sort of negative pressure is getting created inside the board. So when I want to change battery I can not open the Lid, without loosening the legs 4 screws and let some air escape this way. Lift support told me, I had a very good seal and should be happy. I live right at the beach and never take the leg off as most people the have to travel with the board. So I finally did fix it. I drilled a hole 4mm into the latch, treaded the hole with a 4M tread put a plumbing washer under the screw head and it was done. Now I just have to turn the crew a bit and all the air escapes, no more vacuum. This may only be a problem for people that live in a hot climate, my water is often 25-30C warm and the heat of the electronics inside may cause this problem, but it is fixed now. If you do this on your board remove the latch, one of them, and use a drill press to get a pilot hole first then cut your tread be careful not to break your cutter this latch is really hard, slow does it. Her are some pictures so you can see what I did.
Your weight standing on it might have something to do with it.
I have the same issue as do many. I keep a popcycle stick in my bag and stick it in the gap and turn it slightly. Pop. What’s a tread?