Withering Presence interval scaling is broken

Trying to use Withering Presence and just noticed that the scaling on the interval seems to be broken, the gem says duration on wither is 4 seconds and it's applied every 2.7 seconds, when I open the details on it the interval is longer than the duration, even if the interval scaled up with % duration increase it should still be less than the duration.

Seems like it's kinda fixed with the new patch, duration is longer than interval but the interval shows 2.4 seconds prior to activating it and then it goes up to 5+ seconds?

Maybe that's intended but it makes the skill pretty bad, also worth mentioning that wither stacks from different sources interact oddly, a basic expectation would be that I could quickly stack up 50% wither with my wand and the spirit gem would maintain it but instead the stacks fall off quickly. Also it seems like each 5% wither stack is its own thing or something since I can stack up a bunch and then I see like 15% disappear in an instant.