NHF – new heroes for Heroes V 3.1.

Could you send a save file so I can see the problem?

Unfortunately, I deleted it as soon as I realized the skill wasn't working.
By the way, this isn't an isolated case; a friend mentioned that for the Orcs, a certain type of unit, "Warlord," only received goblins for the first 4 days (after leveling up twice), and then it stopped.
I don't know what the difference is, because all the heroes that normally enhance their creatures, and with the mod also boost their growth, work correctly, and even the non-standard ones do too.
In short, the problem only occurs with the 2 heroes described above.