First, I want to state that I really appreciate your work. Unfortunately, this mod seems to have unintended interactions with mods that add genderless animals that are therefore unable to breed, for example the mecha-hybrids introduced in Genetic Rim.
I am not sure if you are already aware of this issue, but if both Humanoid Alien Races 2.0 and a mod adding genderless animals are active, the sterile animals are spawned with as male/female nonetheless. Furthermore, they are - as is vanilla behaviour for normal animals - able to create offspring.
I tested the issue with only a skeleton-selection of mods active and upon removing Humanoid Alien Races, the genderless animals spawned again as intended.

I created a hugslib log, that can be found here:
{Ο ΣΥΝΔΕΣΜΟΣ ΑΦΑΙΡΕΘΗΚΕ}https://git.io/fhQnu

I could not spot any obvious problems in the log (apart from some mods for added scenarios missing), but hopefully you are able to tackle the issue.

If you are already aware, I apologize for the inconvenience. If you need more information, I will try to provide it.

EDIT: Some modded animals are not intended to reproduce, usually due to balance reasons. This mod interacts with said animals, so they are unintentionally included in the vanilla animal reproduction mechanic.