Cannot select model and effort on a new chat

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

Version 26.707.72221

What subscription do you have?

Plus

What platform is your computer?

Darwin 24.6.0 arm64 arm

What issue are you seeing?

When starting new chat I see that my model is gpt-5.5 Medium. When I try to select another model it gets selected briefly, but it quickly resets back to gpt-5.5 Medium.

I can make a change in the TUI app and in the old chants, but it is not working for new chats.

What steps can reproduce the bug?

1. Start a new chat
2. Observe that gpt-5.5 is selected
3. Try selecting another model
4. The model selection gets reset to gpt-5.5

What is the expected behavior?

That the desired model is selected

Additional information

_No response_