I believe the affix “Focus Regeneration” is currently not working. I have a weapon (Gnarled Saw) with Focus Regeneration on it but I am not regenerating focus. I’ve tried unequipping all my gear except for the weapon, doesn’t work. I’ve tried re-equipping the weapon to reset the stat, doesn’t work. I’m also not wearing the ring that prevents focus generation.
So, yeah, I think this stat is currently not working as intended.
Hope this helps. =)