finally tracked down the cause of this zero barrier bug with temerity. like other threads i thouitgh it hads to do with passive regen or changing areas. No the issue is when an elixr or inscense that adds to maximum hp run out, then the temerity bugs out since your hp max drop and it wil look like you have a barrier but your barrier wil only be at zero and occasionaly bounce up ta 100 - 1000 ish then back down ta zero. Unequipping and re equiping the temerity fixes the issue until you use another elixer or incese that raises hp again though.
just played for 3 hours with out using any temp boost to max hp, and temerity not bugged out once.