check and disable SPACE FCTN. on your virtual Teach Pendant. There should also be a warning on the virtual TP "waiting space gets clear". Also check your DCS parameters. Check for any logical signals that prevent robot movement under certain conditions. Use I/O Panel utility (Menu > Tools), add the MAIN production program plus any sub-programs used and simulate a production environment.
EDIT: I just saw you use 2 robots in your workcell. Disable SPACE FCTN on both robots.