An error occurred while saving the commentStefano Panariti commented
I have Mojave and I cannot visualise it either.
I personally use as a valuable walk-around option to right-click on the file I want to share, click on "Open With" and then select Outlook between the available options.
Mac will open a mail window with the selected file attached using the default email account you have previously selected by the canonical procedure Outlook/ Preferences/ Accounts.
Although this option does not solve the issue, hopefully, will facilitate someone's work.