There is some error in browser Console log, it happens after the layout is restarted, but before enemies are created:
Not sure what's causing it, but I think it breaks the pathfinding. Try disabling/rearranging some events, see if you can fix it. Also, if you can reproduce this issue in a small demo project, I advise you to submit a bug report here:
github.com/Scirra/Construct-3-bugs/issues