I'm sorry that you're having trouble adding a resource.
Make sure that you're running InDesign as administrator. Here is information on how to run InDesign as administrator on macOS:
Are you running antivirus software?
In a similar post, a user said that they could open an older file that worked, click the buttons there, and then they would work in a current file:
I haven't haven't been able to reproduce the behavior. It's possible it could be due to a corrupt InDesign file, in which case, I would recommend saving it as an IDML file and back as an INDD file: