Hey JAMFNation! have any of you run into this with Office 2016 for mac?
if you try to open a document from the browser to edit in an office app you get this. I have found two threads on the office help forums:
Office help forum
The issue is that office 2016 does not install the Sharepoint browser plugin I have tried to create a package of the plugins but have not been able to get this to work. Anyone have any Ideas??
Are you running Cisco AnyConnect in your environment? I was having a similar problem last year and discovered quite by accident, that the WebSecurity component of the client was the culprit. Since we weren't using that component with our macs, I uninstalled it and poof, Sharepoint integration started working again.