They put “most” in descriptions to account for instances that are specifically meant to ignore such things (in this case to account for debuffs that are simply not supposed to be cleansed). Tank invulns for example all have “ignores most instances of damage” in their description to account for, say, an enrage or ultimate attack that will kill you even with an invuln up.
I don’t think it’s the intention of the “most” descriptor to allow them to make it completely arbitrary if they will work or not.
