I was testing out the new experimental version on a private server and found an empty stack of .308 bullets. The bullets were visible, but the item counter said 0/20. See the picture below.
In the db\types.xml in the server files, I can see that for "Ammo_308Win" both quantmin and quantmax are set to -1:
This is not the case for any of the other ammunition entries so I suspect this could be the cause.