Symbol conflict. If the user has duplicate symbols on the same data connection (ESU1 and ESU21), this can cause a conflict and MotiveWave may stop sending data to one or both of the symbols. Create a workspace backup before proceeding (File > Backup). Go to Configure > Instruments, search for the particular underlying symbol (ES) and delete the duplicate symbols (please note that deleting any instrument in the Configure > Preferences menu will remove any open charts with this symbol and will delete all analysis and chart data associated with it). Use the magnifying glass search icon to bring this instrument back into the workspace.