See this before at other sites and now got the same issue on a 2016 terminal server. Running Office 2013 on 2016 terminal server. When you load excel the INFOR tab is not on the menu. You need to go to Options / Add-ins / Comm add-ins and tick the box. You need to do this every time you logon to Excel. All other terminal server users are fine so assume this is an issue with the windows user profile? Running latest version of XRL