.css & .xml content not getting updated

Hello,

We have a LTM+AAM VS installed for a Sharepoint application,the VS has Sharepoint policies applied using the iApp template we are seeing a strange issue wherein when the App. developer updates the .css & .xml content on servers these are not getting update on the VS we have also tried cearing cache on the devices but still it is not working also when we apply the default WA-Profile to VS the xml works but the css has never worked.