Stuck not getting key from Hoppers

[Anamiable1]

I bounced the hopper into the horn and they all came popping out, but there was no key rewarded. I have collected 4 keys at this point. This should be my fifth key. I've searched all the branches, and there is nothing

[Lamkin]

No key gets rewarded from that screen. My guess is that you need to check again by the two screens that have little nests with eggs in them.

[Anamiable1]

I had seen a PC walk through of the scene with the Hoppers and assumed it would be similar. Actually, it was the one eyed creature clue you gave to another post that provided my last key! Thank you!