Figured it out. My problem was that I had put a space in my EOS Product Name (“MyApp Test”) Rather than (“MyApp” or “MyAppTest”). This caused a failure deep in the EOS code (UEOSSettings::GetSelectedArtifactSettings(FEOSArtifactSettings& OutSettings)) because I was passing -EOSArtifactNameOverride='MyApp Test' instead of -EOSArtifactNameOverride="MyApp Test" on the command line.
I should have just stuck to the time-honored rule of “don’t use spaces in any names used by code.”