I just tried it again and it worked this time. I had added that key as a plain fido security key and it didn't let me add it as a passkey. So, I removed that k

I just tried it again and it worked this time. I had added that key as a plain fido security key and it didn't let me add it as a passkey. So, I removed that key from the list of security keys and added it as a passkey.