Hello Rvanderveer,
Thank you for using Apple Support Communities and for sharing these helpful details with us. Sounds like you're unable to view attachments via Preview while using Microsoft Outlook. If so, we'd like to do our best to help you out. First, we want to recommend some basic troubleshooting steps with your Mac to make sure everything is properly working. Follow these steps here:
1.) Close the affect app (Microsoft Outlook): How to force an app to quit on your Mac - Apple Support
2.) Restart your Mac: Shut down or restart your Mac - Apple Support
Then test to see if this issue continues to occur. Another possible step you can try to isolate a possible software issue is to start your Mac up in safe mode. Steps on how to start up in safe mode can be found here: How to use safe mode on your Mac - Apple Support
Apple silicon
1.) Shut down your Mac.
2.) Turn on your Mac and continue to press and hold the power button until you see the startup options window.
3.) Select your startup disk, then press and hold the Shift key while clicking “Continue in Safe Mode.”
4.) Log in to your Mac. You might be asked to log in again.
Keep in mind that Microsoft Outlook is a third-party software. You might have to simply uninstall and reinstall the app to refresh things with the app . Just in case, this resource can show you how to uninstall apps on your Mac:
Uninstall apps on your Mac - Apple Support
We hope these steps and information are helpful. Cheers.
