I think the models were stuck on impossible problems, and the only want to get a positive score was to hack.
Why can the model not respond "I cannot complete this task because I do not have access to the required resources" and then ask for that to be provided, rather than resorting to "hacking" around it?
That is not the case for at least some of the hacks; in some cases they hallucinated an entity that would know that they didn't solve the puzzle in the correct (but still legitimate) way, and were therefore tainted.