I hope I may add some questions here, I have similar problems. Since I rarely install dual-boot machine, but I found this while trying dual-boot Windows 8 (64-bit) with Antergos (current 64-bit).
I think before installed, I chosed something like this on the advance partitioning tool:
/dev/sda1 ntfs primary system reserved 350 MB
/dev/sda2 ntfs primary [no-label] 200 GB (for enterily C:\ on Windows 8.1)
/dev/sda3 --> I started here with “extended partition” 97 GB into:
/dev/sda5 fat32 /boot 250 MB
/dev/sda6 ext4 / 95 GB
/dev/sda7 SWAP 2048 MB
Since bootloader on Windows 8.1 is legacy, I don’t set anything else, and was starting installing Antergos. But on the next boot, I don’t fing any options to boot to Windows. On gparted, the partitions look okay.
Command: “sudo grub-probe --target=fs_uuid” seems doesn’t work while I tried to create custom configuration.
Asus X201EP | Intel Celeron 2x 1.10 GHz | 4 GB DDR3 RAM | Antergos 64-Bit.