Been seeing people complaining about this a lot and all I can say is, skill issue. Literally any character can do this its not unique to calico and more importantly, its not a bug.
Creeps being able to be knocked off of rails was a deliberately added feature and its not like they are getting stuck or despawning, it just staggers a wave which is something in basically every Moba ever. Its just a strategy you need to find a way to play against, no different to buying etherial shift to avoid lash ults.