Since the update some of the healers in my guild are having issues seeing threat until they target a player/mob. IIRC the old version would show threat globally until you targeted a mob, but it appears thats not working now. Or is there a setting we need to check to make that function work.
The "global threat" you are talking about is really just a meaningless value, so it has been removed. If a healer generated 2000 threat on 3 mobs, what use is it to know the number 2000? It is more meaningful to know you have 666 threat on each mob, which is what the AoE Mode of Omen2 tries to show. Healer mode does a bit differently, and tries to detect tanks and show the threat vs what they are tanking.
Note that Single target mode is working (it still has lots of bugs) the best at the moment (the mode closest to Omen1), the other modes are not being actively worked on until the more pressing issues with threat calculation and syncing are fixed.