Hi Allan,
Thank you for sharing your experience with us.
Based on your description, hyperlinks even don't work in new documents. If your insert a new hyperlink in a new document, does it work?
Are you using the latest 16.25(19051201) of Office? If you cannot get version 16.25 from Help>Check for update, you can firstly update the AutoUpdate tool via this link.
You mentioned that when opening the same document on Windows 7 computer, the hyperlinks work well. On the Windows computer, try to create a new document, copy and paste the original document content in it, then open the new document on your Mac to see the result.
You may also try rebooting Mac in safe mode to isolate issues with Mac and see if it helps.
If hyperlinks still don't work in Word 2019 for Mac, could you please let us know following information?
1.Have you tried using a different browser to see if the hyperlinks will work? You may change the default browser on your Mac.
2.It seems you get error message when the hyperlinks don't work, please provide a screenshot about it.
3.Your Mac version. (Apple menu>About This Mac)
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Best Regards,
Tina