WTF Recombinator?

WTF is happening with the recombinator? Did it just get nerfed or something?

I just managed to make a Zero mod RARE ring. I figured combining a 1 prefix, 1 suffix ring with a 2 suffix ring (predictable recombination, no exclusive mods) I should get at least one suffix back at a minimum. Should be throw away all the old research from the reddit guide now? I'm so confused, because I just did this same ring recipe a week ago and it worked easily.

Edit follow up: just tried a different combo. Input total 4 prefix, 6 suffix rings only returns 1 prefix 1 suffix. I didn't even think that was possible.