[BUG] Cowork UI freezes mid-response; other chat threads go blank until app restart (macOS)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The Cowork UI intermittently freezes mid-response. The todo list widget updates but the main response area stops rendering — Claude continues working in the background (files are created, tool calls succeed) but no text appears in the UI. There is no indication work is happening.

More critically, this freeze bleeds into other parts of the app: switching to other chat threads shows blank/empty conversations until Claude Desktop is fully quit and relaunched. This makes the entire app unusable, not just the affected Cowork session.

This is happening on both Opus and Sonnet.

• Cowork response area freezes mid-render while backend continues working
• Sending a message in the stuck thread forces re-render (workaround)
• Switching to any other Cowork task renders it completely blank
• Only one Cowork task is viewable per app lifecycle — after viewing one, all others are blank until restart
• Full app restart required to restore functionality, but the one-task-per-restart limit recurs

What Should Happen?

The UI should render properly when I switch between chat threads/tasks, and also when Claude has sent me a response.

• Response text should render in real-time as Claude produces output
• Other chat threads should not be affected by Cowork rendering issues

Error Messages/Logs

Steps to Reproduce

1. Open a Cowork session and start a multi-step task (e.g., one that involves several tool calls and file operations)
2. Observe the response area — it will intermittently stop rendering mid-response
3. Send another message to force a re-render — the previous response appears
4. Switch to a different Cowork task — that task appears completely blank
5. Switch to any other Cowork task — also blank
6. Only one task can be viewed per app restart. After clicking into any task, all other tasks show blank until full quit + relaunch
7. After relaunch, the same behavior repeats: you can view one task, then all others go blank

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.1.3541 (1e65e4) 2026-02-18T19:23:37.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Workaround discovered

Sending a new message in the stuck Cowork thread forces the UI to re-render and display the (already completed) response. This confirms the backend is working — it's purely a frontend rendering issue. So for every thread, I need to send a “hello” ping to get it to re-render. But then Claude responds to the ping, which I also can’t see until I ping again. It’s a terrible loop and waste of tokens for an obvious Claude bug.

What I've tried

• Quitting and relaunching Claude (temporarily fixes blank threads, but Cowork freezing recurs)
• Updating to latest version (multiple updates, issue persists across all)
• Restarting macOS