The simplest way I could find to make a bootable USB Windows installation media from ISO file goes as follows:
plug in USB drive
check the drive device from journalctl
launch fdisk /dev/sdN
mkfs.ntfs -f /dev/sdN1
ms-sys -7 /dev/sdN1
mount -o loop <windows-10-image-iso> /mnt/loop
mount /dev/sdN1 /mnt/usb
cp -a /mnt/loop/* /mnt/usb/
umount /mnt/usb /mnt/loop
remove usb and try
That's it.