I've had the black screen issue ever since the Blizzard update that made Oque break. I recently just found a fix for it.
What I did was go into the World of Warcraft folder (C:/ProgramFiles/Worldofwarcraft) and deleted the entire "WTF" folder.
I then went into the "Data" folder (C:/ProgramFiles/Worldofwarcraft/Data) and deleted the "En_US" folder in there. <-- (probly has nothing to do with it, but was in my process that made it work)
After that I launched WoW and let it repair itself. Logged in and made sure Oque was in the add-on list. Typed /oq in game, and Boom working Oque.

I know im not the only person that has had the black screen issue. I haven't seen any other suggestions on here that have worked. So, hopefully this will work for you guys!

What I did was go into the World of Warcraft folder (C:/ProgramFiles/Worldofwarcraft) and deleted the entire "WTF" folder.

Reset your game client/addon settings. It's the first thing you should do with any UI problem.

I then went into the "Data" folder (C:/ProgramFiles/Worldofwarcraft/Data) and deleted the "En_US" folder in there

Essentially deleted the game completely. 20gb download inc

Actualy no... Reseting game client/addon settings did not work for this issue. And once again no... EN_US does not contain the core expansion/patch files. Took less than 1 minute to repair.