We have recently experienced some issues with Office 365 users on remote desktop having to re-authenticate with Office 365. This is a design behavior by Office 365. Office 365 uses tokens with RDS and after a month’s time these tokes become expired. When they become expired a couple of issues occur. Email is greyed out, messages about product being unlicensed and functionality for Office products is disabled. Simple fix is to re-authenticate with Office 365. Easiest way we have seen is simply opening Excel and going back through the sign in process. Once this process is done, the token become active for another month.