While I was writing this, I realized what the problem was. I figured anyone else who ran into it might benefit. Here's the original post:
I'm using the MacOS build of Rider for .net core development and I've noticed that many of the run/debug/run-anything commands fail because there are environment variables that are set if I run `env` but are not visible in the list of environment variables in the "Include System Environment Variables" dialogs (including in the Unit Test preferences. Some of these are things like passwords and API keys that change periodically and I would rather not go through every configuration and change them there.
These values are exported in my ~/.zshrc file.
And that was the problem, right there. I had opened Rider before any terminal, so that file hadn't been sourced. I moved the variables to the ~/.zlogin file where they will be available immediately.