Windows Codex app blocks sending messages: Couldn't check Agent sandbox status

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

Codex App 26.609.9530.0 on Windows, inferred from the installed app package path:
C:\Program Files\WindowsApps\OpenAI.Codex_26.609.9530.0_x64__2p2nqsd0c76g0\app\Codex.exe

CLI available on the same machine: codex-cli 0.128.0.

What subscription do you have?

Paid subscription. Exact account/subscription details can be provided privately if needed.

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

The Codex desktop app on Windows has been effectively unusable for 20+ days because the app repeatedly fails its sandbox status check and blocks sending messages.

Visible banner:

Couldn't check sandbox status
You can continue in read-only mode

When attempting to send a message, the app shows:

Unable to send message
Couldn't check Agent sandbox status

Clicking Retry does not fix it. Changing modes does not fix it. Closing and reopening the app does not fix it. The UI keeps showing modes like Custom / Ask for approval, and the sandbox status check continues to block sending messages.

The local config has been set to full-access/no-approval:

sandbox_mode = danger-full-access
approval_policy = never

I also tried changing saved app state and closing/reopening the app, but the desktop UI still returns to a broken sandbox-check state.

This is related to Windows sandbox failures such as #17135, but this report is specifically about the desktop app blocking message sending with Couldn't check Agent sandbox status and not allowing a usable fallback.

What steps can reproduce the bug?

1. Open Codex desktop app on Windows.
2. Use a local workspace, in this case D:\Atletia - Prototype\Palantir - Competition.
3. Observe banner: Couldn't check sandbox status / You can continue in read-only mode.
4. Type a message and press send.
5. Observe modal: Unable to send message / Couldn't check Agent sandbox status.
6. Click Retry, switch modes, close/reopen the app, or configure full-access/no-approval.
7. The app still blocks sending messages.

What is the expected behavior?

Please fully fix the underlying Windows sandbox status failure, not only provide a bypass.

The app should either:

1. correctly initialize/check the Windows sandbox status,
2. provide a clear actionable repair path when the sandbox cannot be checked,
3. allow read-only mode to actually send messages without requiring the failing Agent sandbox status check, and
4. avoid silently reverting/rewriting the UI into a mode that keeps blocking the user.

The app should not become unusable for weeks because the sandbox status check fails.

Additional information

This has prevented proper Codex usage for 20+ days while on a paid subscription. Please also advise the correct support path for account compensation/credit for the wasted subscription time, because this has not just been an inconvenience; it has made the desktop app unusable.

Feedback ID from the app issue URL:

no-active-thread-019ed0c1-9a64-77a3-b600-9188b5c375ad