How to replicate this bug:

1.On talent tree you need Salvatory Anchor plus Elevated Gain.
2.Equip heavy armor in head slot first, then in chest slot.
3.Check your resistances.
4.Take off chest.
4a.Check resistances.
4b.Re-equip chest.
4c.Check resistances.
5.Take off helmet.
5a.Check resistances
5b.Re-equip helmet.
5c.Check resistances (in this step you will see that numbers are not the same as they were when you were taking off and on you chest armor).
6.Take off chest.
7.Re-equip chest armor.
8.Your resistances will be the same as in step 3 (or at least should be)

Similar bug is with the Force Shield calculation but I didn't manage to capture exact bug replication steps.
Will make another thread when I'll know for sure how to replicate it.