Claude Sonnet 5.5 not always working

Bug Reports
1

It is returning empty message from time to time. My settings were reasoning enabled, cache enabled or disabled, reasoning level medium or high.

2

Hi @Kuane,

Thanks for flagging that, and apologies for the inconvenience.

Could you share the debugger log links to runs where you saw this behavior?

3

Please see dm

4

Hi @Kuane,

Thanks for sharing the link. From what I can see, Claude Sonnet 5.5 refuses to generate a response, but the same prompt works fine on its own, so the system prompt may be causing the issue.

Could you share the system prompt so I can take a closer look?

5

It is not my system prompt:
It is not receive any response. Is there something wrong with the API settings?

I go back to Sonnet 5 and it works completely fine

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6

Hi @Kuane,

Thanks for checking that. I can confirm there’s nothing wrong with the API settings. The empty message comes from Claude Sonnet 5.5 itself declining to generate a response for those runs, not from MindStudio.

Different model versions can respond differently to the same input, which is why you’re getting a response from Claude Sonnet 5 but not 5.5.

7

Hi Alex,

That’s weird. Generally when a model declines, it will say why and not just return an empty message.

8

Hi @Kuane,

That’s right, when a run errors out, you can see the details in the debugger. However, in your run, the model simply didn’t generate any output