It's called random for a reason. Try going to the Dreadnought and find the taken patrol mission, the one with the skull and crossbones symbol, there is always an ultra within that patrol mission. I have a lot of luck getting exotics out of him.

20 min cool downs I get an exotic every 2nd time I pop a 3oc. Do strike use right before the boss dies if you don't get one go to the tower cash your engrams and kill 10 mins go do another strike I found taking them right after I finished a strike was not working so I wait till I'm at the boss now

Well 10 isn't as bad as you may think. The way I see it, the average exotic from xur is 19 strange coins (13 being the cheapest and I think 24 the highest). 10 3oC is equal to 14 strange coins (since 5 ToC costs 7 strange coins). Rng can be pretty frustrating. Really frustrating. Yesterday I happened to get extremely lucky and get 4/6. But that is rare as hell. Try these things to help. 1: give about 15 min between uses. 2: try on a different character. 3: try clearing your system cache (weirder things have been known to mess stuff up. Worth a shot) 4: make sure you let the event timer for strikes and such run out. Don't just back out to orbit. 5: do not stack them. I believe they took that out. 6: I have the best luck on patrols killing taken champions. Hope any of this helps.

Since the update I've noticed a huge drop off in exotic drops from 3oc in pve at the same time I've heard of big drops in srl and the crucible I smell a bungie rat.

Back to back exotics from toc in srl

Rng sucks 4 ya.