HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

I also haven't experienced the issue of army size not increasing by 1 after a purchase. And precisely because this bug is irregular and difficult to detect, no specific work has been done to eliminate it. But the cause of this bug was most likely in the quick army management functions, and in Heroes of Might and Magic III, these functions were almost completely rewritten from scratch, and the algorithms were greatly simplified. So, those who have encountered this bug should check if it still exists.

By the way, beta 3 has a critical bug that occurs when attempting to transfer the last stack of creatures from a hero to a city. The result is that the creatures are not transferred as they should be in Heroes of Might and Magic III, and further gameplay may result in crashes. So, keep this in mind when testing betas 1-3 and wait for beta 4 soon.