Yes, I have been using Ctrl + Num - for en dash for years, and it was not assigned to ViewZoomOut before (only Ctrl + - was). For some reasons, it was changed to Zoom Out since a few days ago.
To fix this, just as Stephanie said, go to File --> Word options --> Customized Ribbon --> Keyboard shortcuts (customize) --> Categories (go to the bottom, find Common Symbols, then find En Dash and assign the Ctrl + Num - again).
This fix for me. If you are stuck, you may need to "unassign" that shortcut from ViewZoomOut.
Now I have my en dash back.