There are two issues:

1) When mechanoids attack an outpost, either via ship drop or map edge walk-in, the outpost battle is won immediately. There is no error in the logs about this, but I can reproduce it 100% of the time:
https://gist.github.com/47e13e4119dab322a5e170a7e19bc6f6
Regular raids (e.g. from the Viking faction) on the outpost work fine.

2) When my mining outpost map generates, the pawns begin inside of a building that I cannot see into until they try to walk through one of the exterior doors (annoying). There are also often insectoids inside of and surrounding the building, which interferes with settlement defense.

I have some other mods like RimCities and Larger Faction Bases loaded. Please let me know if need to check with them too.