Apple file merge won't launch when using unity collab

When I click “see differences” or “launch external tool” in the unity collab menu, nothing happens when apple file merge is selected as my external merge tool. I’ve switched to sourcegear diffmerge for now, but I’d prefer to use apple file merge again. Is there something that I’m not doing correctly?

Looks like an XCode issue. Run the following command in terminal -

sudo xcode-select -s /Applications/Xcode.app/Contents/Developer

This should fix it.

This is literally the first result when searching for this exact same problem and no answers. Surely someone should know?

Had same issue and this fixed it for me. Thanks.