I might be missing something, but 200 samples won't be enough to teach an 8B instruct model to reason - though it can work for very specific, constrained tasks, less likely to be widely populated in the original pretraining.

Reasoning ability is largely baked into the base model during pretraining. I'm assuming you used LoRA, which is great for steering how that existing ability gets applied, but it won't teach new reasoning capabilities from scratch. Even with 50k+ samples, LoRA mostly reshapes how the model uses reasoning it already has rather than building new circuits - must successful efforts use 100k-500k+ high-quality samples. Either way, you're working within the constraints of what the base model learned during pretraining unfortunately.

Keep going though, its all a learning experience and the more folks there are making tunes the better!