Above all the frustrating spells that exist in all of D&D (even worse than hold person in IceWind Dale) is how some weakling paladins from Kelemvor's domain are able to dispel all magic on Safiya, her being level 30, having spell resistance 35, having protection from spells, empowered spell mantle. In IceWind Dale my company had no superior saves or special abilities to resist charms, but here in NWN 2 i have everything and that is why this is BS!
This must be some bug, if not this is an extreme example of disbalance.
You're right. This is a known bug. If you check nwn2 wiki, you can get a more detailed explanation about this bug.
Apparently the spell doesn't actually check the caster's level but rather character level. This is especially bad for high level gameplay like MotB when everyone has added monster levels to their character sheet and the difference between caster levels can be wide. More, under certain circumstances, the game doesn't even check your own caster level, thus the dispel (when cast by hostile creatures) will always win no matter the odds. Even a lowly githyanki can strip all of level 30 Safiya's spells...it really is that bad.
And it is exceptionally bad for campaign like MotB that discourages you to rest and re-apply your buffs every few encounters.
My suggestion; beware and put extra care for any creatures/npcs that can dispel, however weak/insignificant it's supposed to be.