We've been working on this for a number of weeks now and are really struggling to find anymore potential solutions.
The issue is, we're not seeing the conversation history or missed conversations in the Skype for Business application. We are, however, receiving the conversation history in Outlook and that seems to be working fine. We can see user availability in Outlook and S4B is putting users as DnD when they're in a meeting so that all seems to be working fine.
We're using Exchange Server 2010 on premise and Skype for Business Online.
Any help or suggestions would be much appreciated, we're pulling our hair out over this!