Sharepoint sharing from within word, excel (Possible Mac-only issue?)

Trying my luck in the forums, since google has come up dry!

File is located in a sharepoint library, and can be shared perfectly well using 'share' or 'copy link' from within the library.

However, if I try to open a file in excel or word app, the frame fails to load (as shown in screenshot). The same happens if I do it 'file>share' as well.