Have you set a FIDO2 PIN?
FIDO2 != OnlyKey PIN and is entered on the keyboard.
More info:
ssh-with-fido2-how-to-set-up-which-pin-code
cant-setup-onlykey-as-2fa-device-with-ssh-keys
I don’t know which disti you use.
You may have to reinstall onlykey-cli & onlykey-agent according to PEP 668.