Unlike other commands, the run and run-cycles commands will not block the command line when run interactively.
In script branches, the command will not block execution of the script branch when no count argument is passed - in this case the next command of the script branch will be executed as soon as the simulation has been started. When the count argument is present, the command will block execution of the script branch until the simulation is stopped (due to reaching the specified time or for other reasons, for example, stopping on a breakpoint).