We noticed similar problems tonight with Bloodboil and 68254. After a few wipes because no one could see each other on the list, we all updated and relogged. The next attempt everything was working fine. The attempt after that, the ranged dps could not see any of the tanks (2 warriors, 1 druid). The tank druid mentioned on vent that she could only see herself, not the other warriors. Not sure about the warriors, whether or not they saw themselves.
Okay now we've more or less fixed the problem, at least it seems that way!
First, we made sure ALL raidmembers deleted the Omen addonfolder, AND all the omen.lua and omen.lua.bak files in the WTF folder;
then we all downloaded Omen rev68250.3, and everyone selected 'Blizzard MTs' as datasource in healermode!
All that together made it possible to get an accurate threatlist on the 2rd bloodboil try,
and we got our firstkill ^^
Only at the beginning of the 2nd try, 2 of the 3 tanks were at the bottom of the list, but they got on top after some phases.. the druidtank always was on top, and as I just saw in the video I made, the tank who has the aggro isnt the first on the list!
but at least all 3 tanks were on top after some time ^^