The proxy settings were set in the local.properties in the VSE server and some of the VSMs stopped working when going to the live invocation step.
When the proxy settings are removed, these VSMs started working and others started failing.
All supported DevTest releases.
The settings added in the local.properties are global. In this case, all the VSMs deployed to this VSE will go through the proxy set in the properties file.
Open the Virtual Service in the Workstation and add the 'Configure DevTest to use a Web Proxy' companion to the VSM that needs to go through the proxy server.
Save and redeploy the service.
The proxy settings can be removed from the local.properties server for VSE.
More information regarding the Configure DevTest to use a Web Proxy companion, refer to section "Configure DevTest to Use a Web Proxy Companion" in the documentation of the DevTest release you are running.