Guess the red in & outputs just had it reversed then: https://forums.factorio.com/128890

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 ...

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.