Sekhmet's basic attack benefical effect removal

Would someone care to explain to me how this works exactly ?

In the skill description it says "Remove One Beneficial Effect from each enemy". From this I infer it removes one blue effect with 100% chance (from each opposing toon). If there is more than one blue effect, one is selected at random and removed. The duration of the effect should not matter. Do I understand this correctly ?

I use her quite a lot and I've noticed that it doesn't work in the arena quite properly. The chance is not reliably 100%. At first I thought it may correlate with effect duration, i.e. when the effect exceeds a duration of 1. but maybe it is related to the presence of golden effects ? if a golden effect is present, and randomly selected as the one to be removed nothing happens as she can remove blue effects only ? I don't know, I've got to observe more I think ... Did anybody else notice this ? Am I overlooking something obvious ?

update:
So apparently it's never working when perfect immunity is present. Is it supposed to work this way ? Not sure if the same is true for "regular" immunity, will post an update once I'll get to see it.

Hey Liu,
This observations are correct, so I have noticed, when the description just says "remove / steal beneficial effects" refers only to blue effects, so perfect immunity will rather prevent that from happening.

For this it takes someone who removes / steals golden effects, or all the effects of the enemy, or at least the perfect immunity, or even a set of talismans, such as Valor for example.

So far, the only character I've noticed (I can not remember the exact description now) who ignores the perfect immunity to remove beneficial effects as The Madam