Oddly enough, when a new city is founded, outposts retroactively default ownership to these newer cities if these are deemed closer. Yet even stranger, upgrades currently being built by an older city are (not always, but often?) to which the outpost had belonged are still built by that older city -- using, however, the production values of the newer city! Thus disrupting the ownership of an outpost by city A through city B while city A is still upgrading the outpost causes city B to keep the work in progress in its queue, but have it completed according to the (usually significantly lower) production values of city A.

Solution: Either 1. when a new city is created, outposts do not change ownership, or 2. Production values should be calculated at their actual values for those cities who are actually producing them.