ChatGPT Atlas: Thinking effort resets to Instant while web retains Medium/High

Description

In ChatGPT Atlas, the Thinking effort setting does not persist. If I select Medium or High, it later returns to Instant.

The same OpenAI account behaves normally in the regular web version of ChatGPT: Medium/High can be selected and the setting is retained there. This makes the problem appear specific to Atlas rather than to the account or plan.

Steps to reproduce

1. Open ChatGPT Atlas on Windows 11.
2. Open the Thinking effort selector.
3. Change the setting from Instant to Medium or High.
4. Send a message / continue using Atlas.
5. Check the Thinking effort setting again or open another chat.

Actual behavior

The setting returns to Instant instead of remaining at Medium/High.

This is reproducible repeatedly.

Expected behavior

If Medium or High is selected, Atlas should retain that setting until the user changes it.

Comparison with ChatGPT web

Using the same account in the normal ChatGPT web interface:

• Medium/High can be selected normally.
• The selected Thinking effort is retained.

So far, the issue appears limited to Atlas.

Troubleshooting already tried

• Checked for Atlas updates.
• Fully quit and restarted Atlas.
• Signed out of the OpenAI account.
• Quit Atlas, restarted it, and signed back into the same account.
• Selected Medium/High again after signing back in.

The behavior did not change.

Environment

• OS: Windows 11
• Product: ChatGPT Atlas
• Reproducibility: Repeatedly reproducible
• ChatGPT web: Works normally with the same account

Workaround

Using the regular ChatGPT web interface when Medium/High Thinking effort needs to be retained.

I can provide a screenshot showing the Atlas Thinking effort selector (Instant / Medium / High / Extra High) if useful.

Start by reproducing the setting reset in ChatGPT Atlas on Windows 11, then compare its behavior after sending a message and opening another chat. Done means Medium or High remains selected until the user changes it; the payload does not name a repository file or test to inspect.