Enough people are having problems with 4 dimms to call it a non isolated issue. I've 4x8Gb. Trust me, it HURTS having to use only 16Gb of the 32Gb I bought... even if the performance difference is almost non-existant for what I do with this computer.
At the moment, the solutions given by Gigabyte are of the "did you try turning it off and on again" type. I guess they're gathering information from everyone's support tickets and running their tests. They'll end up fixing it sooner or later. I just hope it gets fixed through a BIOS update rather than having to RMA all our mobos.
If you really need to go Gigabyte for any reason (hackintosh), you should probably wait and see if this gets solved. If not, well, it's your call, but the Asus Maximus Formula is as good as it gets, it's in the same price range and the build quality is mindblowing.