Hard to tell without seeing the project but the red balls that are not moving might not be able to find a path, and you have no event to deal with that.
Add in "on failed to find path" and then have it find path again. (although i see your notes on the right)
You could also do a test for objects that have a path but aren't moving, if true set them to move.
There could be many other reasons though.
Also for event 17 you are better off using the timer behaviour. So: on created - start timer once off for 300secs
new event: Red_ball on Timer destroy red_ball