Hi,
another flash problem I have, may the third party problem too.
I use the YongNuo YN-622C ETTL radio triggers on my 7D before and after getting the 7D II they didn't work

Nearly all exposures where full flash exposures.
If I set the flash control to manual it worked, but ETTL, even with a Canon 430EX II flash on the YN-622C device didn't work.
I would say Canon changed the wireless flash control interface a little bit, so third party flashes could have a problem.
In my test the pre flash for ETTL was too bright, so the camera will send a full flash needed command too the flashes and the picture is overexposed. With the use of the internal flash as wireless master the pre flash isn't that bright.
It's not a Canon problem, but I think it's good to know.
In my thread
http://www.dpreview.com/forums/thread/3747630#forum-post-54671707 a user say that the Pixel King ETTL flash devices have the problem too, but this devices have a update function so they may be work later.
Bye
Markus