I downloaded catalyst from the link pasted at the bottom.
My flickering problem just magically went away. I'm not sure what did it. I used CRU (custom resolution utility) to lower the resolution to something like 3740x2160 and found that the flickering would stop. infact it seemed to be a problem with the horizontal refresh rate or something because if I put the monitor in potrait mode, no flikering. I eventually went back to the native 3840x2160 at 30hz and it hasnt flickered since.
It could also be that some windows updates fixed the issue. I'm not sure which.
On your issue, It sounds like one adapter is physically disable and the catalyst software detects that and dis-allows crossfire. While you could give it a try and download another version of catalyst, its likely you'll need to have the actual laptop checked to see why one adapter is disabled.