If anyone is getting a black rectangle when selecting text in Microsoft Word 2020, I may have found a solution.
The cause is Windows Speech Recognition application.
To solve the problem you need to:
1. Open Window search bar by pressing Window's flag logo button.
2. Search for Windows Speech Recognition, a little bar will open on top of your screen.
3. Right click the bar and select Off: Do not listen to anything I say
4. Right click the bar again and select Exit
It may take a few seconds to work!
If it doesn't work at first try repeating the passages above and wait few minutes.
Uninstalling Word or Repairing or Reinstalling won't solve this issue.
I hope this post can help someone.
--
Andrei8989 🐲
