I have 2 of the V2 and they don't leak at all. Fact is that QC on these China product is less that perfect. Sounds like you have an air leak somewhere. Maybe an o-ring issue or some part of your tank is out of spec. I seem to recall I had a tank long ago that drove me crazy with leaks and I finally found that the glass was ever so slightly out of round. Very small manufacturing defects can be responsible for your problem. I would have sent the tank for a replacement if that happened to me. Yea, I know that is a pain but it is not worth fighting a problem you can't see.
It's his second V2, same problem. I also have multiple V2's and no problems. My wicking is not always the way I want it, but still it doesn't leak. Well it leaked once, I closed the AFC all the way before I filled it and then that is when it did leak. After that I always make sure it is full open before I fill. Before that I used to get very minor flooding after a fill, now never. He did try with the AFC full open, but for him that doesn't work either. I found with my Berserker that if I do the opposite of the advice and leave the AFC open it doesn't leak, close the AFC and it makes a mess as soon as I open them. But it still does flood even with the AFC open so I went back to bottom filling the Berserker, just too easy and 100% dependable to waste my time trying to do it any other way.