I've seen many examples and used the 1.1st version for a long time but in the new documentation they suddenly suggest including the 1st version like so:
<script src="https://appsforoffice.microsoft.com/lib/1/hosted/Office.js" type="text/javascript"></script>
Looks like Microsoft Outlook Add-In won't initialize in MAC after updating the application to it's newest version. To fix this you need to change the version of the Office App script you include in your add-in from 1.1 to 1.
I now also found out Microsoft mentioning doing it in the Dev Center Blog:
You may have seen examples that reference the /1.1/ resource, https://appsforoffice.microsoft.com/lib/1.1/hosted/office.js. That’s fine for now but from now on, you should use the /1/ resource.