I've been using it on Full Tilt, works just fine for me. Have you made sure to enable "Everything" in your chat settings? HI runs from chat data, not from HH data like most other tools, and requires maximum chat info to work. That's true for any site you use it on.
I run HI along with PT3 Beta simultaneously on Stars and Tilt, no conflicts or problems. And since PT3 doesn't support Cake skins, HI is the only tool I have currently for my SportsBook account. It works very well, and the stats it calculates match exactly those displayed by the PT3 HUD, which is impressive considering the data is acquired from different sources. The only HI stat I've sometimes questioned is WTSD%, which occasionally seems to indicate that I've been to showdown more than I really have. I haven't bothered to compare against PT3, probably because when it happened it was on SportsBook which PT3 doesn't work with.