Once it gets below a point, the game doesn't let you restore them to the starting and out of combat max.
Does this happen from certain status effects or as a result of those?
I don't know what to tell you that the file doesn't. I don't do anything speashul in combat or that anyone else doesn't do in "danger" areas. Only save edit I remember is freeing Reaha without losing her. I hope someone fixes it in future builds because it gets really dangerous on Phadera.
you're not really providing any information to work off of. what are you expecting your max shielding and health to be at? what fight did you notice an oddity? did you use any consumables? did you change equipment?