You might be giving it too much leeway.
Opus and Fable are more trustworthy, but even today I find they very quickly go off the rails for research tasks if I don't give them short chunks of work.
They're not ready for prime time automation of research (and before someone mentions the math results, that required absurd amounts of computation time and has immediate feedback in the form of Lean)
I guess when you ask these things to take on the role of a senior scientist it picks up some natural stubbornness in the training data.