Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
A while ago an indie game I was following had to shut down because one of their devs left the "company" and had a lot of the artistic and/or models rights or something like that. Maybe something similar is happening here: the dev of this stuff left and they didnt get to keep their work.
Maybe its like the Halo 2 E3 demo (nothing of that ended in the final game) or its hidden just like banners are, who knows.
Create your own conspiracy quest