Hi there, @Cquinn.

I want to make sure this is taken care of, and I'd like to redirect you to the best support group available to get this addressed right away.

I can see that you've already performed some troubleshooting steps, like setting up the Acrobat Reader as the default, to fix the issue. Since you won't still be able to print payroll checks in your QuickBooks Desktop for Mac, I highly recommend contacting our support team. This way, they can further investigate this matter further and provide other troubleshooting steps to get this resolved. They can also create an investigation ticket if other users are experiencing the same.

To reach them, you can follow the detailed steps shared by my peer KlentB above. 

You might want to read this user guide to learn how to handle transactions in QuickBooks Desktop for Mac: User Guide for QuickBooks for Mac.

Please know you can continue to reach me here with any additional questions. I'll be around to provide further assistance.