Random is not bypassing heroic lockouts - FAIL
Contrary to what blizzard blue postings state, the random heroic instance feature is not bypassing heroic instance lockouts. If you've already done a heroic for the day, and you later get a random heroic for that instance, you are screwed. The bosses will be non-existent.
I'm hoping this is an isolated glitch, or else a known bug, and is not now intended to be the way things work.
I did heroic Nexus earlier, and just now got Nexus as the random heroic. I ported in, cleared trash to Omorok, only to discover Omorok was MIA, backtracked and Keristraza MIA also.