Autopart error while trying to create dualboot Windows 8.1 with Fedora 26 on separate drives

Hi all!

I seem to have some trouble creating a dualboot setup with Windows 8.1 and Fedora 26 on two separate drives.

I started by reducing the size of the NTFS partition on one of the non C drives to allocate space for Fedora. I've included a screenshot of disk management to create an overview of the situation, below.

During the Fedora installation, I selected "Automatic" for the partitioning scheme. Unfortunately that gave me the following error:

autopart failed: sdb may not have enough space for grub2 to embed core.img when using the ext4 file system on partition

I am rather clueless about what this means. A Google search also did not help.

What could be the cause of this?

Thanks in advance!

After some more searching I found that it may have something to do with GPT (the disk is GPT formatted). I tried to create a manual partitioning scheme with a BIOS boot partition, to no avail. It keeps throwing similar errors at me.

I have found something that appears to work at first glance. However, I am very hesistant to go this route as I don't want to break anything (I don't understand partitioning/bootloaders well enough).

What I tried to do is to select the drive Windows is installed on as the boot device (in other words, I did not create any partitions on this drive, I merely selected it for the bootloader). Having done that, the installer happily accepted the configuration without errors. I did not proceed with the installation however for the aforementioned reason.

Is it safe to do this? Why does this work? Is there a better way to solve the issue? (I am trying to understand the issue better.)