When the advanced cauldron only has a single chest, it'll refuse to run because there's not enough space.
Adding a double chest fixes this, but there should be enough space left for the XP.
Steps to reproduce:
Make a Advanced Cauldron with 1 chest.
Try to run a recipe.
Only tried this with recipe 2 so far, and the factory facing east-west.
When the advanced cauldron only has a single chest, it'll refuse to run because there's not enough space. Adding a double chest fixes this, but there should be enough space left for the XP.
Steps to reproduce: Make a Advanced Cauldron with 1 chest. Try to run a recipe.
Only tried this with recipe 2 so far, and the factory facing east-west.