Wellwater Phylactery mechanics

Can someone explain how Wellwater Phylactery flasks works, because I had character with CI allocated and when I used this flasks my character instantly died, but in description of flask it says that it removes percentage life on use. When my CI character has 1 life that's 100%, flask removes 10% life on use, which means that it should remove 0.1 life on use, isnt that correct? In hideout flasks does not work.

(Edit: I did some testing with the flask. Certainly it will kill you on use through CI, even with life recovery, which I tested with both about +90/s life regen and .8% life recovery. It is a mana flask, mana flasks are not useable while on full mana, so that may be why it is not useable in the hideout for you. I was able to use it in the hide out, it consumes the flasks, without the character dying. Hideout is a safe zone, it may not protect against everything, but in this case it appeared to prevent the death when I was using the flask. In combat area, the flask was killing CI character instantly, and I do not know a way of preventing it from doing that.)

I believe the characters life is an integer, it will not go to .9. Non integer effects might sum together on the same frame before the change to life is calculated, but the character will not be able to be on a life value between integers and in POE they often round the numbers up. So it's possible that may be rounded up to 1. Blood rage is similar to this mod and the expedition mod that removes percentage life when hit. I think it may be possible to run that with CI, so I'm unclear how it works, it may get rounded down in that case.

I'm also not sure if there is a way to get these mods to work with CI or not with other effects. I think it may be possible if you have some recovery that counteracts it.

Example of people talking about counteracting percentage life loss while on CI.
https://www.reddit.com/r/pathofexile/comments/1ip0tac/does_ci_mitigates_it/

I was in a recent thread talking about topics related to this, but am unclear on the answer, it seems there that it was an unrelated mod that they were dying to, and it was possible for them to run the life removed on hit mod while playing CI.

https://www.pathofexile.com/forum/view-thread/3861314