Persistent 'Other Block Reason' error on Nano Banana Pro (gemini-3-pro-image-preview) with reference images

Gemini API
1

Hello,

I am experiencing a persistent and unresolved ‘Other block reason’ error on Nano Banana Pro (gemini-3-pro-image-preview) in Google AI Studio and need help identifying the root cause.

Issue:
Every image generation attempt with reference images results in an immediate block with the message: ‘The model response was blocked, please clear your chat or start a new prompt to continue.’ The chat session locks after every block, forcing a new session each time.

Account & Session Details:

  • Model: Nano Banana Pro (gemini-3-pro-image-preview)
  • Date: 07-05-2026
  • Token usage at time of block: 7,254 / 131,072 (well within limit)
  • Resolution: 4K | Aspect ratio: 3:4
  • Number of reference images: 3 to 5 garment flat-lay images (no explicit or sensitive content)

What I have already tried:

  1. Starting fresh new chat sessions after every block
  2. Simplifying the prompt to under 100 tokens
  3. Removing reference images one by one
  4. Rewriting the prompt in plain natural language with no instruction-style formatting
  5. Turning off Grounding with Google Search
  6. Creating a new API key
  7. Testing with text-only prompt (no images) — this worked fine and generated an image successfully

Key Finding:
The block ONLY occurs when reference images are attached. A text-only prompt with no images generates successfully. This suggests the image scanner is flagging the reference images, however the images are standard fashion garment flat-lay photographs with no people, no faces, and no sensitive content.

This workflow was functioning correctly on the same account with similar reference images prior to today. The sudden onset of blocks with no change in content suggests either an account-level flag, a model-level restriction, or a backend issue.

Could you please help investigate:

  1. Whether the image safety scanner has become more aggressive for this model recently
  2. Whether there is a known issue with gemini-3-pro-image-preview and multi-image reference inputs
  3. Whether my account has been temporarily flagged due to multiple failed attempts in one session

I have attached a screenshot showing the block error, the prompt, model selection, and run settings.

Thank you.

3

Hi @foraiuse

Thank you for sharing this,
Looks like the screenshot did not get attached,

I have DM’ed you for these details