I had an issue with Outlook messages. I could not drag and drop an email to a folder in Outlook 2016 (Office 365). Then I noticed that I could no longer highlight some text and then drag and drop that text in Word to cut and paste it, like I always could.
I tried safe mode and the Esc key trick and neither worked.
After much searching online, I gave up and uninstalled Office and re-installed it (64bit version) and now finally drag and drop works in Outlook and Word as it should. I recommend doing that: uninstall and reinstall. Because my profile was already in the
Win10 registry, everything hooked back in perfectly and I didn't miss a beat once I logged into my MS account to verify the license. Super weird. Hope this helps.