An update went through, but unfortunately didn't bring the necessary image files. So I downloaded the game from the website and stole the Images folder from that, which fixed the problem. For what it's worth I tried doing it piecemeal first, adding the missing ./Ships/AICarrier ./Ships/AIGuardianLaser and ./Ships/AIGuardianRaider folders (they weren't in the Steam install at all), which gave me zoomed in images but no mini icons (which I quick tested with the handy F1 cycle).
Also for what it's worth the Steam version at the moment will restore "_guardsNotAttacking2.sav" on a re-verified cache, which from the name I would guess is a file left over from the beta test.
I hope some of this information is helpful, and thanks for the great game!