Auto Print may stop automatically printing for a variety of different issues. Here is a list of troubleshooting steps you can perform in an attempt to resolve this issue.
1. Make sure that your emails are saved locally on your machine. Some services, like Office 365, stores emails in a cloud archive. Though these emails may appear in Outlook through search, they are not actually on your local machine. FOr example, if you must press the 'More' button in Outlook to load the email, it is not saved locally on your computer. Make sure the email is saved locally.
2. If you are trying to print the email from a PST file or Outlook archive, that archive may be corrupted. Create a new PST file. Then copy all of the emails from the old Outlook archive to the new PST file. Then remove the old PST file from Outlook. Finally, update Auto Print and test it again.
3. Restart your computer.
4. Office issues and updates or Windows updates may cause an issue. In this case, perform a full online repair of Office. Then reinstall Auto Print and test again.
5. Perform a clean install. Follow the directions at this link to perform a clean install: https://sperrysoftware.freshdesk.com/support/solutions/articles/5000617123-how-to-perform-a-clean-reinstall-your-add-ins
6. Download and install the Microsoft C++ redistributable located here: https://docs.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist?view=msvc-170
7. Ensure that the SSOutlook.dll is registered in Windows. Follow the instructions here: https://sperrysoftware.freshdesk.com/support/solutions/articles/12000085921-how-to-re-register-ssoutlook-dll-or-ssoutlook64-dll-