Aahh!!! the dreaded mBases.ini, Nooooo take it away
it's been a while since I last did anything with the mBases.ini, last time was to rebuild a 10Mb one, nightmare.
No NPCs at all - FL stops reading the mBases.ini from the first error it finds, this can be as little as one silly typo hiding in the file, or as much as a completely screwed base entry. If none of the debugging tools can find it then you have a couple of choices, do as FriendlyFire suggests and swap entries around, or jump in and out of bases in game, trying to find the last base with NPCs, or spend several hours eyeballing the mBases.ini trying to find the bloody error.
Only Dealers - This is caused by an errant base entry in the mBases.ini, duplicate entries cause this, but so does having an entry for a base that doesn't exist in the Universe.ini.
**shuffles off with a new headache**