Assume that you enable response group service (RGS) in a Microsoft Skype for Business Server 2015 environment. When you run the Enable-CsTopology cmdlet to have the changes published, some RGS agents can’t receive toast notifications even their presence status is available.
This issue occurs because the presence watcher is reset when the Enable-CsTopology cmdlet is invoked.
To fix this issue, install the following cumulative updates:
May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, Response Group Service
May 2017 cumulative update 6.0.9319.281 for Skype for Business Server 2015, core components