Read-only HFS+ on Windows 10 with boot camp driver question
I finally solved it!

This literally took hours out of my day, but I now know what the problem was. It turned out that the drivers actually were installed. by verified this checking for the presence of the following files:

C:\Windows\System32\Drivers\AppleHFS.sys
C:\Windows\System32\Drivers\AppleMNT.sys


The reason that the drive was unreadable is because they were encrypted with FileVault. I disabled FileVault in OS X, and when I booted into Windows again, the partition was mounted.

There might be a way to use FileVault and Boot Camp together, I'm not sure. I read in a few places, however, that if you enable FileVault after installing Windows with Boot Camp, you can have your drive encrypted and accessible from windows. (This is just a hunch however, I'll have to look into it more)