I added a beam interceptor and a protective field to my starbase. I fought several battles within the radius of this base. During combat, enemies were able to inflict full damage to my ships. Also, in the after-battle report, I noticed that I did not receive any starbase bonuses. Oddly enough, I have fought battles within enemy starbase range that indicated the enemy received these bonuses.

This is sort of an unfortunate bug, since I thought one of the neatest features was the idea that a starbase could add bonuses to ships, adding a very cool "fort" feeling to the game. Alas.

IIRC, it's not that it needs that specific type of defense....it just needs to have a single piece of defensive equipment on board. So if your starbase adds +3 to beam defense, you can have as little as a +1 missile, mass driver, OR beam defense and you'll get the +3 to beam as well.

Blif

It's likely calculated as a defensive "bonus", but if your defense is 0, then naturally multiplying anything by 0 results in 0.