[4.15 p2] MSAA and Alpha2Coverage problem

Okay, well I am going to get clarification on whether or not it is officially supported in the 4.15 release, but I entered a ticket to have the information clarified and uniform.

Once I get the answer, we can investigate more into the issue you are experiencing. I will say that the large disclaimer at the top of the documentation link you provided applies to all the associated features, so it is expected certain features are not production ready yet.
Thanks,