[BUG] BUG: Cowork Linux sandbox fails to start on Windows — persists after all Hyper-V service fixes

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?

Environment:

• OS: Windows (company managed)
• App: Claude Cowork mode
• Error: "Workspace unavailable. The isolated Linux environment failed to start."

Steps taken (with IT admin, full admin access):

1. Set vmms (Hyper-V Virtual Machine Management) → Automatic ✅
2. Set vmcompute (Hyper-V Host Compute Service) → Automatic ✅
3. Set hvhost (HV Host Service) → Automatic ✅
4. Verified via PowerShell: all three services Running + Automatic
5. Restarted Claude, started multiple new sessions
6. Sandbox still fails on every attempt

Result: File tools work. Only bash/Linux sandbox is broken — across all sessions and after full restart.

Related issues: #50997, #52359, #55404, #55649, #56145

Request: Local Hyper-V config appears correct. Please investigate server-side provisioning or advise on fix for managed Windows environments.

What Should Happen?

The Linux sandbox should start successfully so Claude can execute bash commands and Python scripts in Cowork mode.

Error Messages/Logs

Workspace unavailable. The isolated Linux environment failed to start. You can still use file tools directly.

Steps to Reproduce

1. Open Claude Cowork mode on Windows (company managed)
2. Start a new session
3. Ask Claude to run any bash command
4. Error appears every time: "Workspace unavailable"

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

april 30 2026

Claude Code Version

Cowork desktop app (not Claude Code CLI)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This bug occurs in Claude Cowork desktop app (not Claude Code CLI).
The sandbox has never worked on this machine. All Hyper-V services
confirmed Running + Automatic via PowerShell. Bug appears systemic
based on related issues #50997, #52359, #55404, #55649, #56145.