Split from this thread.
The problem with the attachments greyed out has not been resolved. I can see from this forum (running since March 2016) and other forums on the web that the issue is widespread, and impacting productivity. I have tried Office Insider Fast, no fix, reverting and no fix.
I can see that there are a few from Microsoft on this thread, so I'm offering my time to help resolve the bug by providing whatever logs, information, diagnosis needed. This shouldn't be be necessary as the problem is persistent, widespread and repeatable and impacts people across various macOS versions.
I'm no software engineer, but if this isn't a problem for the Windows Outlook Client, Mac Mail client, iPads or iPhones (or web mail) connecting to exchange server, then it's likely an issue with the Mac Outlook Client.
Multiple people (including myself) have suggested that this issue is related to slow or interrupted connectivity. You can reproduce the fault by disconnecting the LAN while downloading the attachment. If you quit outlook and then start up again, the Sync sometimes fails to recognise the email text has been downloaded but no the attachment (you get All folders are up to date).
PLEASE FIX.
Regards,
Mark.