I have an iMac with an internal Fusion Drive, and I've since wiped that drive installed macOS on an external Thunderbolt SSD for speed.
I'd like to install Windows 10 on my iMac's blank internal drive, preferably using Boot Camp (I'm aware there are other methods).
When I start Boot Camp Assistant, it says "External storage device attached" and tells me to remove all external storage. I can't of course, since it's referring to my SSD which macOS is actually running from. I assume this is just some sort of warning to make sure you know what you're doing with your target drives so,
Is there a way to bypass the message and carry on with the installer? Or do I have to go some other route like using a Windows install USB?