This is likely because all outputs are only by chance, and not guaranteed. EMI doesn't like to do calculations for results based on RNG for trees.

Is there any plans/solutions?

Hi, the problem currently is that with chanced outputs, you cannot make a tree that can list of cost at the end, since you can't promise that randomness will occur ever, so the range is effectively 1 batch to infinity. It is on the to do list to more properly support partially chanced recipes. For instance, in this case, charcoal will always make black dye, so it could be used whenever black and not gray dye is used. It would also be possible to have a chanced output be at the top of a tree, since its outputs are not required for anything else, it's the result. But, at the moment, the solution to these problems are still under development.

So will chanced recipe output be in a medium part of a tree?

In the future they will be able to show up in the middle as long as the chance is not on the required output. If possible, I might also attempt to allow trees with chanced outputs to form without counting costs, as well, so they can be fully used.

Gonna close this as it's a future feature expansion and there is no proper bug that needs fixing, works as intended for now.