Master surgeon life flask don't queue but don't give recovery life or effet

Hi I don't know if it is a bug or I misunderstood the effet. But when I use my life flask with master surgeon(pathfinder) I don't get the life recovery from it if I use two or more life flask in the same time.

So if I use two life flask I just lost the second recovery life. This is the same thing for effet like immune to poison when use. I need to wait the end of first flask before get the effet.

I play in ruthless crucible, maybe is the source bug?

not a bug, same flask effects do not stack.