Gemini-3-pro-preview with reasoning token = 0 and no response

Hi,

Im working on an OCR task, sometimes I will get no response. I check the reasoning token, it is also 0.
I use OpenAI SDK with high reasoning and high resolution image.

One finding of me is: this case will more likely to happen if logical conflicts exists in my prompt. If I adjust the prompt dedicatedly, the problem can be solved.
But I still wonder why such case happens.