From this, I wonder if the pendant might only work once per long rest, as opposed to every time your HP drops? I don’t think it says that on the description, but just a guess from your outline of the problem.
Though I also had some issues with the Helmet of Grit last playthrough, which also triggers once HP drops below 50% but sometimes did and sometimes didn’t. Though I never managed to work out what was going wrong there, either, so all I can do is feel your pain!
I have been using Grit for a while during this run and have not had any issues. Also have a thief using it in a different run. (Thief with THREE bonus action is cray-cray, especially when combined with the GameBreaker... oops I mean... LineBreaker Boots. (:
I'm working on a vid showing a squishy bard killing EVERYTHING with Linebreaker,Grit, and the L4 sorc feat to get Expeditious Retreat. When the dang pendant works... it is a thing of true beauty O_o
