We are seeing an intermittent issue with remote users using Blast Extreme through a UAG where Skype thinks the user is still Away. You can not manually set it to Available and the Skye client must be quit and relaunched to set the status properly.
When a user connects internally with a Dell Wyse P25/5030 zero client using PCoIP it works as expected. Skype properly detects the user is connected and sets the status to Available.
We are running Horizon 7.1, Horizon Agent 7.1 on Windows 7, UAG 3.0, Horizon Client 4.5.1, Lync 2013 Standard Edition and Skype for Business 2016.