Probably this is just a very dumb and obvious mistake but I cant make the recipe combinator output a recipe...

Vanilla game, with only creative mod and crafting combinators. A constant combinator outputting the signal of copper wire to the recipe combinator and... nothing happens!

https://imgur.com/a/GNfCNeB

I just realized.... that the output values do not show up in info panel on the right side.
The combinator was always outputting, they were just not visible in the info panel.

Yeah, that's one of the limitations that using a two-tile combinator has, unfortunately...