I followed the recipe using casting basin and a casting spout to pour in the molten steel with a hopper below to get the item out. After a the block hardened the block just disappeared from the basin without outputing any item out of the hopper.

same bug

same issue here

yup, people on my server are losing their steel! The thing is that once it starts happening, it's happening for everyone on the server, all the ingots just disappear. The only way to mitigate this is to restart the server, but that's extremely inconvenient.