Sorcery Ward Bug?

Whenever I use a hp pot or mana pot my sorcery ward shield goes from 3786 to 1884 on witchhunter is my character just bugged or am I missing something. I'm not taking damage from anything and just testing in my hideout using grenades then pressing mana pot and I lose like almost half my shield for no reason. Someone please help or explain thanks!

I think it has something to do with weapon swap not sure.