All devices are gone from the NetMonitor dashboard. The devices are still visible on the "Device Management" dashboard, but not on the "Performance Browser" dashboard.
In the Foglight Management Server log file the following can be found:
2016-07-27 09:21:50.667 WARN [http-exec-2085] com.quest.wcf.components.domainviewer.DomainViewer - Error executing function "system:infrastructure_netmonitor_performance_browser.getNetMonitorDeviceState" in view: 'system:infrastructure_netmonitor_performance_browser.performanceBrowserTabManagerHome' for user: 'xxx'
com.quest.wcf.publicapi.code.FunctionInvocationException: class "com.quest.lamp.netmonitor.utils.ObjectStateFunctions" not found for Java Function definition id=system:infrastructure_netmonitor_performance_browser.getNetMonitorDeviceState