At a client we noticed that after our last round of patching the RD Web Access web feed broke. All of our servers run 2012 R2. The broken feed was evident on Windows 8.1 and 10 PCs/laptops that connected using RemoteApp and Desktop Connection and also on iPads (makes sense because these all use the feed).
Removing KB3098785 fixed this for us (Security Update for Microsoft .NET Framework 4.6)
Note: Our RD Web Access server is also running RD Gateway. I have not tested whether the RD Web Access feed breaks on a server with only RD Web Access installed.