The Foulborn stat “50% of overcapped Lightning Resistance” is not working correctly. The value is listed under Increases, but it is not being applied in the calculation of Total Mana. As shown in the screenshot, PoB calculates 805% increased total Mana, but the base Mana is only being multiplied by a value of 8427/2896 = 291%.

My suspicion is that Mana is being calculated before a value for Lightning Resistance is determined, so PoB treats it as 0 and only updates it after the calculation.

For the stats “Mana to Energy Shield,” the calculation works correctly later on.