Sorry this took so long to get back to you with!
I've done a bit of testing, and the only thing that I can see that would break this part of the post-battle event is if the switch for losing to the boss Liquidator is on.
However, the only way that switch should be on is if you lost to her while fighting her, through running out of HP, but that also should result in a Game Over.
I don't suppose you've been activating random switches through a save editor, have you? Not that there's anything wrong with that, I just need to know if it's something that can trigger accidentally as well.
Hmm, I remember losing to her, but it was through sex rather than Hp loss. I remember healing as often as I could during the fight between waiting and shifting around to find the position that she doesn't smash my skull in.
Thanks for looking into it this much though, and sorry if it has been robbing your development time. Also, what is a save editor? (Joke, but I don't have one nor do I know how to use it.)