I cant really put my finger on why or what triggers it.
But AMR seams to have issues counting the 0.16% of the shoulder enchant towards the crit immunity.
It keep suggesting Def gems after reaching and surpassing the cap.
I my BiB below, i see 3 def gems that could be split gems instead, or 1 split gem and switch shield enchant.
We account for resilience when calculating whether you are crit immune.
Defense is still a good defensive stat above that threshold – sometimes the calculations like getting a little more beyond the cap. The difference between swapping out one defense gem for one stamina gem is infinitesimally small… can’t really say one way or the other which will make you tougher. They are about the same.