OpenAI has completely obliterated the existing documentation for September API versions of o1-mini and o1-preview, in typical legacy-destroying fashion. It refers to models without version.
https://platform.openai.com/docs/guides/reasoning#limitations
It is more intertwined and confabulated because the documentation seems to refer to a o1-mini that is a replacement for o1-mini. Rolled out to an undocumented number of tier 5 users by unknown qualifications.
The correct role to pass to the newest version of o1–preview is “developer”, and system being accepted is a fluke contrary to docs (yet it seems like a different role name was never needed at all since they are transforming inputs to API models) and the prior 2024-09-xx that still include the documented o1-mini only accept “user” (and “assistant” as needed for conversation continuation).