Canon EF lens compatibility issues

I've seen several threads discussing which canon EF lenses are compatible with the various Black Magic EF mount cameras. I've been having considerable issues using my Canon EF 24-70 V1 with the BMCC. Some times it will work fine. Other times the aperture will lock up. I power the camera down, remove the lens, put it back on the camera. Sometimes that fixes the problem. Sometimes it is does not. Is anyone else having similar issues in 2015? I had planned on buying two Ursa Minis this year, but Im hesitant to commit now if these cameras aren't going to work with the lenses I own. Thoughts?

I asked Black Magic if they were aware of compatibility issues, and they didn't have any recommendations or info to offer. Could really use some help regarding this issue.