Upon further investigation (Copy-pasting things from random internet webpages like a good HN would do), running the following two commands seemed to help get th

Upon further investigation (Copy-pasting things from random internet webpages like a good HN would do), running the following two commands seemed to help get the Yubikey SSH running a little more reliably with Github for me, including with Tower.app after making sure it has the correct PATH setup: `eval `ssh-agent -s`` `ssh-add` Without the eval ssh-agent command, `ssh-add` fails to add the ECDSA-SK key since Mac OS' SSH implementation doesn't seem to natively support it. I don't understand how running eval ssh-agent resolves it because that shouldn't persist very long with Mac OS' own SSH agent trying to run.