Minecraft 1.12.2
Forge v14.23.5.2838
Metal Transport v2.4.0
Better Chesting v1.1.1

• Combining a chest containing items with a Minecart will cause you to lose all items in it.
• It happens with both the Vanilla Minecart and the Minecarts from Metal Transport.
• Chests can be placed in the Minecarts by right-clicking or crafting, but both cause item loss.
• Metal Transport comes with an API that can be used to add compatibility.

I might add vanilla minecart compatibility, but only when right clicking it. I don´t think I can transfer NBT when crafting

Ok, whatever works is fine with me.