I’m very new to Audacity, and I’m currently trying to record my Korg MS-20 mini into it. I’ve hooked up the audio out on the Korg to my Focusrite 18i8. I can hear the keyboard when I hook my headphones up directly to the Focusrite, and the Focusrite control shows that it is receiving a signal, but for whatever reason, when I try to record after selecting the focusrite as my recording device, nothing happens. If anyone has any ideas on what to try I’d very much appreciate it . Thanks! 
Audacity gets its sound from Windows, not from Focusrite. So go into the Windows sound control panels and make sure the Scarlett is there, selected and you get the Windows bouncing sound meter.
Then start (or restart) Audacity and see if you can get the same thing in Audacity > Edit > Preferences: Devices.
The Scarlett Solo and its cousin the Lightning are simple, native Mono devices which are a snap to connect and make work. I have the Behringer version. The minute you get into multi-channel recording (beyond 2), or other tricks, you start to worry about special driver software and operating system compatibility.
Did you install the Focusrite drivers for your 18i8? Did they say they would work with Windows 10? They have to say that somewhere. Generic or older Windows driver software can have problems on Windows 10.
Let us know.
Koz
Thanks for the prompt response. I selected the Focusrite for sound from Windows, and oddly, it works for vocals just fine. I checked up on my drivers, and I believe they are the most current ones available for Windows 10, but I put in an inquiry to Focusrite just to make sure. It really is the strangest thing. I tried disconnecting the microphone so that the only active input is the input from the keyboard, but it didn’t make any difference. Please let me know if you have any other ideas.