Still Using 2018r2 can't build for iOS under Catalina

It’s the last version my expired Pro license is valid for. The “Build” and “Run” buttons are greyed out despite having Xcode 11.4.1 and its Command Line Tools installed in a NON-STANDARD location that Xcode-select points to.

What is my problem?

If you hold your mouse over the disabled buttons, a tooltip might have a hint for you. I’m not sure when that hidden thing was added though.

It says “Xcode and required command line tools are not installed.”

Could this be caused by Catalina removing the “/usr/include” directory? If so, I have an external Mojave boot drive I could use instead.

It’s possible. Developing for iOS is a very “you must have the latest and greatest” environment, and that unfortunately includes Xojo.

From this page:

You won’t be able to build apps for the App Store with Xojo 2018r2 as Xcode 10 is required. Xcode 11 will be required as of June 30.