Simply put, any items on the network from an ME sorting interface are not visible to another network looking through a storage bus at an interface on the subnetwork with the sorting system on it. I have a feeling this may be linked to #316

The ME Sorting Interface is likely going to be removed in the future. It's causing quite a few issues and was never balanced in the first place (it basically replaces the need for several storage buses by one block).

I am using the Agrarian skie 2 pack and having the same issue. I have a wall of sorting barrels with one sorting chest. I have a wall of compacting drawers with two sorting chests. I can have 1 ME sorting interface connected to one of the walls. As soon as I connect both walls I can no longer craft.