"Nothing to run on"
What does it mean when you see "Nothing to Run On" in the configuration?

I actually have a second project that works but I can't really figure out the difference. The one that works looks like this:

but I have no idea what those checkmarks are next to the two possible target configurations. What makes that appear? I have a cmake profile set up for both hardware platforms, near as I can tell the configurations are all identical.
This has been driving me nuts. I actually created a sample program that you can try:
https://github.com/wz2b/platformio-test
This is with CLion 2020.1.3, the latest platformio plugin 201.8743.17, and the latest platformio 5.0.4b1
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Hello!
If you do `Tools | CMake | Reset Cache and Reload Project`, do you get any errors in the CMake tool window?
No, it succeeds.
I think I figured out the problem but I don't understand it. If I go back into the execution configuration and I create a dummy target, then I have a build and a run button again. I saw that Z_DUMMY_TARGET in the PlatformIO examples but I didn't understand it. I think it's just a CMAKE target and it's telling CLION this is what to build, because the PlatformIO "targets" aren't real targets.
See, the problem is really this. Look here:
https://docs.platformio.org/en/latest/integration/ide/clion.html
Now look at my run/debug configuration:
What is it that makes theirs say their target name (mzeropro) but mine says "Nothign to run on" ?