It may be that something got corrupted during the upgrade that affected this one scheduled job..
Try setting up a new schedule for the workflow again.
If the problem persists after setting up a new scheduled then send an email to support@alteryx.com and mention case 294106.
Include on the email the following:
- exported sample workflow file (Designer > Options > Export Workflow)
- screenshot of the error
- screenshot of Designer > Help > About
- RuntimeSettings.xml File - C:\ProgramData\Alteryx
- Service logs - C:\ProgramData\Alteryx\Service
- Engine Logs - C:\ProgramData\Alteryx\ErrorLogs
Keep in mind that the directories mentioned above are defaults installation locations and it may be different depending on how it is on your Alteryx System Settings