I've been playing a couple levels so far, and I've noticed something.
I'm not sure if this has to do with the games coding itself, the custom levels, or something to do with the combination of the two, but seedlings have been staying on certain planets after being ordered to go somewhere else. The same thing has been happening with send all, and send a certain amount. I've been forced to reroute seedlings through other planets then back through another route to get to the same place.