Windows desktop app: second/follow-up message hangs indefinitely in Work and Codex after Sep 5 update

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

26.901.51231

What subscription do you have?

Plus

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

I am experiencing a regression in the Windows ChatGPT desktop app where the first message in a Work or Codex conversation works, but the second/follow-up message stays processing indefinitely and never completes.
The issue appears to have started recently, likely after the latest Windows desktop app update.

What steps can reproduce the bug?

Feedback ID: no-active-thread-01a07a50-f278-7413-84ad-afebdb0420d9

Open the ChatGPT Windows desktop app.
Open an existing Work or Codex conversation, or create a new one.
Send the first message.
Wait for the response to complete.
Send a second/follow-up message in the same conversation.
The second message stays in a processing/loading state indefinitely.

What is the expected behavior?

The second and subsequent messages should send and receive responses normally, just like the first message.

Additional information

Troubleshooting already attempted:

• Restarted the Windows laptop.
• Uninstalled and reinstalled the ChatGPT desktop app.
• Tested multiple different chats/projects.
• Tested the same Work conversations in the browser.
• Tested on the iPhone app.

Start by reproducing the issue in the Windows desktop app using the listed steps and feedback ID no-active-thread-01a07a50-f278-7413-84ad-afebdb0420d9. Compare the Work or Codex conversation behavior with the browser and iPhone tests; done means second and subsequent messages complete normally.