Shield Specialist/Shield Tech perk, that causes Energy/Heat blast hit extra 3 enemies and increases damage reduction by 2%, while Ion cell/gas cylinder is active. Bug is that its 2% extra resistance isn't imposed until you change instance after respec. That's likely because at pre-5.0 you had to switch on Stances manually, while now Stance is switching on automatically, and likely it's done while respeccing BEFORE Ion Shield/Ion Screen ability is trained, thus Ion Shield/Screen checking fails at stance setup.

Solution: remove Ion Gas Cylinder/Ion Cell requirement for Ion Screen/Ion Shield.