The game this occurred in was funny, but the bug first:

Races who had no ships or stations reported that the most powerful one they had was that of the race above them, indicating that a value wasn't cleared.

I played a mostly-random game as a custom race, and went up against Terran, Arcean, Drath, and Drengin AI races on a tiny map, difficulty Normal, tech normal.
There were 17 habitable planets in 9 systems. Each AI colonized the second planet in their home system, and then STOPPED. I took 9 planets in 5 systems.

I then formed alliances with all but the Drengin.

There were no wars.
I was the only race to engage in trading.
I was the only race to form alliances.
The Terrans took two resources, and deployed two other influence bases in my space. They had at least one ship, a Terran Defender that I never saw.

It seems all 4 AIs decided to go purely for the Tech victory, at the expense of everything else, handing me bigger and bigger tributes as the game progressed. (Each of them was somewhere along that branch, but not very far, at the end.)
Eventually, while persuing an Influence victory, I was able to form an alliance with the Drengin, winning the game that way instead.
The Terran Defender was listed as the most powerful ship for the Terrans in the military summary.
The other 3 races, below that, listed the Terran Defender as well.
At the bottom was my custom race, listing one of the ships I'd had waiting for the attack that never happened.
I did at least get to fight a pirate battleship and fleet!