I was having a similar problem, the first time I got the same MBR error, rebooted and started getting a generic error to check the install logs.
What fixed this for me was to format the partition using diskpart, opened a command prompt on the "select partition screen" and formatted the partition. I formatted it on NTFS and after that it allowed me to select the partition and installed successfully there.
Here my steps:
- Start the install and go to the partition selection screen
- Press Shift+F10 to open a command prompt window
Execute the following commands:
select disk 0 (assuming 0 is the disk where you created the bootcamp partition)
select partition 4 (assuming 4 is your bootcamp partition)
format fs=NTFS label="Windows 8" (I didn’t use QUICK)
- Press refresh and you should be able to select the partition.
This solution doesn't seem to work when booting from the bootcamp created USB. I managed to make it work by buying a USB SuperDrive and booting from the Windows disk (not EFI). Worked like magic after that. Also quick format works too - will save you 2 hours on a 1TB disk.