I'm using MBP retina early 2015 high sierra. I'm trying to install windows 8.1 through boot camp. After following all the instructions (i.e. specifying iso path, partition size, downloaded support files automatically etc) in boot camp assistant, when the machines restarts to install windows, the machine reboots into OSX instead of windows. When I checked the bootcamp partition in disk utility, it says used space is 71MB and nearly the full partition size is free. The used space I think is consumed by the windows support files.
https://support.apple.com/en-us/HT201457
Please can anyone advise what could be wrong?
I do not know if my experience can help you or not.
My Macbook was too old for any Windows newer than Windows 7.
Therefore, besides downloading the Apple Support Files for Windows through BootCamp in a USB stick, I partitioned with Disk Utility the inner HD and formatted one part in NTFS.
Then I used a DVD with a .iso of Windows 8.1 and the Mac booted and installed (with a lot of time and patience) Windows in that NTFS partition.
( I had made several DVDs with Win 8.1. and only one booted, do not know why).
In this way I managed to install Windows 8.1 and used the Apple support files to have most of the hardware working.
I then upgraded to Windows 10 and used some windows driver tools to find updated drivers where some hardware still made problems.
One must be cautious however with those windows driver tools since not all their recommended drivers work as they should.
On several occasions I had to repeat the whole installation procedure after having installed a wrong driver and losing for instance WiFi.
So, with a lot of patience and time it is still possible to have Windows 8.1 or 10 (even in an old Mac) in cases in which the BootCamp assistent is not fully working to help us.
Ed