Im having the same issue. My setup was a plexdoor box that closed around the entity while it was still on the rail, then a shootout rail to disconnect, and a pickup rail on the receiving entity. It all works as intended, The plexdoor enclosure keeps the entity in place when the shootout rail disconnects it, then after five seconds the pickup rail attaches it the next entity. The problem is that at that point, the object im moving is now stuck. Even breaking the rail docker wont free it, Only after I restart my game will it unfreeze.