There are a few reasons why you're unable to run payroll in QuickBooks Online. This includes an incomplete tax setup or other missing employee information. To make sure all information is completed, use the following links to review your Payroll setup in QuickBooks Online:
You will see an alert in the Dashboard if there are missing information for taxes. Click on the link to see which information needs editing. You can also tap the Gear icon and use Payroll Settings to verify tax setup completion.
For missing employee details, it is indicated with the yellow alert which hinders payroll processing. See this:
Kindly update me on the result as I want to make sure this is resolved. I'm also here if you need further help with this. Have a good one!