As the thread was older and about gmail, I have moved your message as a new post for more clarity.
I understand you're using the OFFICE 365 add in with a Mac and you cannot load your templates in Outlook, is that it? Can you confirm you're using Outlook for Mac as an email client, or if you are using Outlook on the Web?
If you're using Outlook for Mac, can you confirm if this is working with Outlook on the web?
Could you also uninstall and reinstall the add in? If this is still happening, could you try disabling all other extensions to see if this works and then reenabling extensions one by one to see which one would be conflicting?
The issue is not only about the templates, but rather that the add-in doesn't recognize there are recipients, so all features when sending emails are not working: logging, tracking, inserting templates or snippets... When clicking on these features the add-in says there are no recipients and asks to add one.
I already uninstalled and reinstalled. Managed to make it work, and the next day the issue was back again...
Could you confirm if this is working with Outlook on the Web? and trying disabling all other extensions to see if this works and then reenabling extensions one by one to see which one would be conflicting?