Adobe Acrobat Reader DC Version 2019.010.20069 not working intermittently

I have a user that uses Adobe quite heavily. He has a recurring issue that nothing I do seems to fix. The issue persists at a rate ranging from a couple times a week to a couple times a day.

Issue: When my user tries to open an email from his Outlook, nothing happens. The PDF won't open, no error messages, etc. Nothing crashes. He then reboots his computer and then he doesn't have the issue for a while. Opening PDFs work normally.

What I've tried:

- Updating the user to the latest version (version number in title)

- Running an Adobe repair

- Uninstalling Adobe, rebooting computer and then reinstalling Adobe

- Making sure Adobe is set as the default app for .pdf files

- Checking system and application event logs for any errors coinciding with the time of the issue - nothing showing there.

What else can I try?

User is on OS Win 10 Pro