Passkey signin worked great for about a month, but has now dissapeared and its back to passwords. How do I get back to using a passkey?

There's a possibility that the passkey has been deleted, @chris455.
 

To resolve this, let’s sign in to your Intuit account and add a new passkey. Here are the steps to follow:
 

1. Open your QBO account.
2. Click your profile and select Manage your Intuit Account.
   
3. Go to the Sign in & security menu.
4. Select the Passkeys section.
   
5. Choose Add a passkey and follow the prompts. 
    

Also, ensure that your browser is updated updated so that the passkey feature works correctly.
 

If you want to check which devices and locations have accessed your account recently or to identify any suspicious activity, refer to this article: Update your Intuit account’s security settings. Scroll down to the Monitor your account activity section.
 

Our team is always here to help if you need anything else.