I noticed the similarities to your issue, but since that was about the input and also mentioned as fixed, I posted this as a new topic.
I also saw you pointing out that you didn't check the other orientations, so I quickly went through them to confirm this only happens in this specific situation.

When the selector combinators face east, all red wire shadows go to the input. I checked the green wire, other orientations, and other combinators, but this only happens to selector combinators facing east.