Update:

I just downloaded an app to simulate a middle mouse click. I then added a secondary keybinding to Toggle Filter to use middle mouse button and this allowed me to set the filter for cargo wagon slots.

This is not what I'd call a good solution, though.

I just noticed today that you can no longer filter cargo wagon slots. I have a cargo wagon on a track, click to open the cargo screen. I used to be able to Command-right click any of the cargo slots and filter that slot to a certain item. My "Toggle Filter" keybinding is set to Command-rig...

I'm on version .17.25 and I just noticed something while building a rail yard. I had all elements placed for a 20-space loader yard then went back and added circuit wires to detect material levels from the chests and disable the rail stop if there are not enough materials. Then I made a blueprint of...