The crafter block uses a special method to move its result into an inventory and fabric api doesn't patch this method like it does with the dropper and hopper, causing transfer-api-only storages to not accept items from crafters. It might also be a good idea to check that the transfer api is able to correctly insert into crafters as it has special item spreading logic.

Orginally reported as MattiDragon/ExtendedDrawers#124