When starting a new chat, thinking effort defaults to low and cannot be changed intil chat starts

[kiranjd]

What version of the Codex App are you using (From “About Codex” dialog)?

26.422.71525 (2210)

What subscription do you have?

Pro

What platform is your computer?

Darwin 25.3.0 arm64 arm

What issue are you seeing?

I open a new chat in any of the projects and try to change the thinking effort from low to anything else and does not change at all
I start that session and stop, change thinking effort, submit again

export-1777539781449-social-feed.mp4

Here's the config.toml

model = "gpt-5.5"
model_reasoning_effort = "medium"
model_verbosity = "low"
show_raw_agent_reasoning = true

approval_policy = "never"
sandbox_mode = "danger-full-access"
personality = "friendly"

What steps can reproduce the bug?

1. New chat
2. Try to change thinking effort from low to anything else
3. Gets stuck in low and does not change

What is the expected behavior?

when i change the thinking effort it should change seamlessly

Additional information

No response

[github-actions]

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

• Model selector broken on new chat #19192
• Model selector is stuck on GPT-5.5 with medium intelligence in chats and some projects #19316
• Can not change model or reasoning effort for new thread #19139

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