Hi there, @k-freeman.
I want to ensure that your one-time PIN code get's address you can work on the accountant's copies that you've received.
The account's security is our top priority. Passwords, on their own, are not always secure if someone gets your password, they can access your account and make unauthorized changes. This is why we enhanced our security in the system.
Multi-factor authentication is an extra layer of security, in which you may be asked to enter a one-time confirmation code, which provides extra protection for your password. The code will be sent to your email or mobile device.
In this case, I recommend contacting our Customer Care Team since the code is not working. They have the tools to further isolate this matter and provide a fix.
Here's how you can reach them:
1. Open QuickBooks.
2. From the Help menu, choose QuickBooks Desktop Help.
3. Type Contact Us in the search box. Then, click on Contact Us at the bottom.
4. Select the way you wish to connect with support (Chat, Call back, Etc.).
For your reference, you can also check out this article for your guidance when working with an accountant's copy in QBDT: Convert the accountant's copy to an accountant's working file.
Be sure to let me know how else I can empower you to make QuickBooks work the way your business needs. Thanks for coming to the Community, wishing you continued success.