This seemed like such a perfect test case, I thought I ought to share the save with Tech Support. At this save point, I have no reason to believe the colony AI isn't working as intended.
Scenario: One colony ship was manually controlled, loaded up and sent to a colony, two have correctly loaded and are on their way to correct destinations on auto. One appears to be travelling to load up correctly for one of the queued Deep Ocean planets and one has just finished building (Quiet Ruse), but, unnoticed by me, is travelling to pick up a population that is a poor choice for any of the queued planets (though it has one that would be +10, which seems to be the threshold for this behaviour). As everything was working perfectly up to this point, 3 more planets have recently been queued.
Less than a minute after unpausing, you can see things starting to go really wrong, fast:
- AI starts building extra colony ships without saying anything, despite colonization policy being set to suggest (Still not sure if this is working as intended if you flag a planet on new colonies tab).
- The advisor suggests building colony ship(s) as well.
- Double colony ship building bug can occur from the above.
- Because Urukablis 3, the target for Eager Challenge has just come under the territory of another empire, when it gets there it reroutes to a (sensible choice of) nearby colony. (I think this example can reshuffle other ships to bad targets)
- At some point, without any warning or notification, the AI cancels most of the colony flags
- Stop and reset automation for the ships travelling to the wrong planets and try and queue better candidates up; The game will usually decide not to reroute those ships to those planets and will usually continue them on their way to poor candidates. Sometimes it will reroute them, sometimes it might reroute another ship that is half loaded.
- Manually send a ship to a better candidate and compare results from not doing this; it often results in the subsequent ships that were loading colonists changing their destinations regardless of population
- As above, but after flagging that candidate on the new colonies screen. Different results will occur if you reroute a ship before or after the game has tried to build another colony ship.
- Queueing colonies for the excess ships being built/already loaded and seeing what they do. Usually nothing for a long time and then heading to a poor choice of colony.
- Seeing if a nearby flagged colony takes preference over a higher suitability one for assigning a colony ship to. (No discernable pattern here)
- Seeing if a full ship with an ideal population that is idle takes precedence over building a new one (No discernable patter here)