I've had the same problem with Office 2019 (click to run) since September. [Is it possible, it's only a click-to-run problem??]
When I try to copy Word text to PowerPoint, an error message appears. It's not PowerPoint's fault, though, as I can copy text/graphics from all other programs to PowerPoint. It's also not possible to copy Word text to OpenOffice 4. This means that something in the Word clipboard isn't working.
What I've already tried:
Reinstalled Office 2019 --> no success
Deleted this registry key HKEY_CURRENT_USER\Software\Microsoft\Office
--> It worked for two days, then the error came back (a friend also has the same problem and the error came back after a short while after deleting this registry key).
Started Word in Safe Mode --> that works, copying is possible again. I then restarted Word without add-ons --> the error reappeared, it's not the add-ons.
There are many internet sites where the error has been reported, but Microsoft hasn't added it to its to-do list yet, probably because it doesn't occur on all devices. Interestingly, it affects the entire Office product family. I know users with Office 2016 who have the error, as well as with 2019 and Office 365.
Anyone who has the error, please post here to bring it to MS's attention:
https://feedbackportal.microsoft.com/feedback/idea/c85d63b1-b1ee-ef11-a4dd-7c1e52c1c6b2