I am not very experienced with acolyte so I am going to ask very generic question to see if you are not missing something.
Do you have +X necrotic spell dmg somewhere? Passives, or weapon? That could mess with the tooltip
Have you tried on a ennemy?
I do have a dagger that offers +64 spell necrotic damage, but I’m not sure how that would affect the tooltip so immensely.
I agree with your assessment that the dps tooltips are unreliable. The entire character sheet needs a do-over. There’s an absolutely immense amount of stats and numbers needed for this game - their current method of providing extra information is unhelpful at best, and downright frustrating at worst.