Support explains that, without access to Windows, decryption works for any email address EXCEPT outlook/hotmail ones. For these the link will not appear (as they assume you use the windows desktop application). Note that the outlook web email or android app do not support decryption either. Since I don't have a Windows device there is absolutely no way to open these emails.
So I guess in doing this Microsoft is teaching a valuable lessons never to use their products as even they themselves put compatibility with other email providers as a higher priority then support for the emailsemail addresses they themselves provide.