It’s a failure mode that comes from pattern matching without actual reasoning.
Exactly. Also looking at its chain-of-wordvomit (which apparently I can't share other than by cut and pasting it somewhere), I don't think this is the same as GPT 4 overfitting to the original river crossing and always bringing items back needlessly.
Note also that in one example it discusses moving the duck and another item across the river (so "up to two other items" works); it is not ignoring the prompt, and it isn't even trying to bring anything back. And its answer (calling it impossible) has nothing to do with the original.
In the other one it does bring items back, it tries different orders, even finds an order that actually works (with two unnecessary moves), but because it isn't an AI fanboy reading tea leaves, it still gives out the wrong answer.
Here's the full logs:
Content warning: AI wordvomit which is so bad it is folded hidden in a google tool.