A sorting machine next to an inventory will work:

A filter inline will work:

A sorting machine inline will not work:

Dependent on in which mode the Sorting Machine is in that's true or not. Sequential All/Any Stack and Random All stacks don't work, while the other tree modes do. This is intentional, as with all stacks for example, you can't supply all stacks at once when the sorting machine is in-line.

I'm guessing the pull mode does not matter but event in "Any Stack/Item (With Default)" the sorting machine does not accept items.