The cargo ship is getting stuck when it is leaving the corner of the map. 

Map: Procedural Map
Map Size: 3000
Map Seed: 1006434092

I loaded up that map and spawned 11 on that map with no issue, including one in each of the four corners.  What grid did it spawn in?

mine as well it auto spawns
Map: Procedural Map
Map Size: 2500
Map Seed: 353335

I will give this a test.

Merged post

I ran 15 and they spawned in the 4 corners of that small map.  I realized I had version 1.1.18 so pushed that out to release, let me know if this persists with that version.