[Snake]

A hunch, but that might be due to one of those updates that made DR stacking be multiplicative. If seems to be starting from your NatDR (I.E DEF/RES), rather than the first instance of bonus damage reduction you get, which was probably what we all requested in that forum post asking for it.

Things should be like NatDR + Bonus DR 1 * 2 * 3 * 4... Or else things like that may happen, where the instance of DR is your only, but you don't benefit fully from it.