Quote Originally Posted by Shyluv View Post
I have only noticed it do that on Warriors. I assumed an ability they have negates HoT spells or something.
Probably Wrath. Wrath boosts healing received (same as Convalesce), so if you hit them with regen at 4 or 5 stacks, you have to wait until they build to 4 or 5 stacks again before you can reapply.

//EDIT: Poster above me got it. Need to stop leaving things open and not refreshing before posting.