Windows 7 USB Tool not recognizing external HDD as USB device

Jul 4, 2018
9
0
10
Hello. So I recently wanted to install Windows 7 onto my computer. I have the ISO and the USB tool. I don't have any flash drives above 4GB so I'm using an external USB HDD (150GB) to install the installation ISO to. (I'm not installing the OS itself on my external HDD, but just the ISO).

Anyways, with the Windows 10 Media Tool it recognized my external HDD to install to, but the Windows 7 tool cannot. Any advice to help me install the ISO on my external HDD?