In the RDS web access screen you may sometimes come across broken or wrong icons for the published applications.
I have found two possible reasons for this.
The application is no longer available on the RDS host. In this case you can see the application as being crossed out in the RemoteApp manager.
The other occurred when I removed some applications. All the application switched to the default icon. When I looked at the RemoteApp manager all the applications were listed correctly with the correct Icons. If I specified a windows Shell icon then it would update the icon. If however I specified an application icon it would not update. To resolve this you need to either remove and re add the application or change the application alias. After this the icons will show up correctly again.