oS I installed from a usb drive in the normal way
What's the "normal way"? How are your partitions set up? From what you write later it doesn't sound like you just let it use the whole disk, as you have Windows 10 and Linux Mint on it too.
john155 and usually I just run the boot program which updates the grub
What's "the boot program"?
I use the OS uninstall program just to prove that the system is recognizing the install
Yeah, okay, but Solus doesn't have an "uninstall program", so I'm still unsure what you mean by that.