Error: "sign_and_send_pubkey: signing failed: agent refused operation" (Mac OS)

Did it work before and broke later or did it never work in the first place?

Is it only Shuttle where it doesn't work or also when you run any SSH request from the terminal (e.g. ssh -T git@github.com)?

I have a similar problem with Core Tunnel and and Ansible when using rsync over ssh between two remote hosts.
The one thing all these use cases have in common is no interactive terminal - and all of them used to work.

Using ssh directly works fine, but anything that doesn't have a terminal attached hangs and then fails.

Using ssh directly with -T also works for me in iTerm.

1Password 8.10.5-10.BETA (8.10.5-10.BETA.148644)
macOS 13.3.1 (22E261)

I've just updated to nightly, and it works somewhat better.

I can now do single connections, so my main tunnel in Core Tunnel works.
But if I try use to multiple keys in rapid succession 1Password crashes. (You should have received a few crash reports from me about that).

1Password 8.10.5-12.NIGHTLY (8.10.5-12.NIGHTLY.148947)

Latest nightly fixes the issue for me.

1Password 8.10.6-5.NIGHTLY (8.10.6-5.NIGHTLY.150178)