I was wondering why clay soldiers don't drop when I kill them. In older versions they would drop, so why don't they drop now? I have a few other mods installed, so it may just be mods clashing. But is this part of the game or not. Their items drop when killed but they do not.

Are they spawned from the Nexus?

Nope. I started a survival world and I found a clay hut and I tried to kill and collect the soldiers inside, but they just died, so I spawned the items of them in.

Yea, soldiers from the huts don't drop themselves. The only soldiers dropping themselves are the ones spawned from you while you're in survival mode. Or those spawned by dispensers.

Pretty sure the generated clay hut versions spawn soldier NBTs akin to the nexus