The mana regen component of devoted familiar and allegiant familiar seem to be blocking insidious harvest.
*Edit -- wasn't the familiar -- clicked it off and tried insidious harvest and still no go. Will test further.
*Edit again: Ok I think it is the clicky effect Brilliance of Might II on the resplendent pauldrons that is doing it. I have all of my normal buffs and clicked off that....then indsidious harvest magically worked.