Manaconvert not doing enough damage

[Xzerion19]

Manaconvert, the effect of the manastone is only doing 39 hp of damage. When I went into the spell editor it was listed as doing 60hp of damage. I had to raise the dmg in the editor to 91 to make it do 60 dmg in the game.

Why is this? Is there some kind of hidden formula server-side that I am not aware of? The effect type listed in the editor is 0:HP [DD/per Tick] and the effect forumula is 100:min. I tried changing the Effect type to 69:Total HP but then no damage was being done at all.

Thanks