CoworkVMService fails to start on Windows 11 Pro 25H2 — ERROR_INVALID_FUNCTION (1066) even with Hyper-V enabled

Environment

• OS: Windows 11 Pro 25H2 (Build 26200.8037)
• Claude Desktop: 1.1.7714.0 (MSIX install)
• Hyper-V: Fully enabled (all components, HyperVisorPresent: True)

Problem

CoworkVMService continuously fails to start with Windows Event ID 7024:

CoworkVMService service terminated with the following service-specific error: Incorrect function. (ERROR_INVALID_FUNCTION / 1066)

The service enters a loop: START_PENDING → crash → restart → repeat indefinitely.

Steps taken

1. Restarted Claude Desktop — no effect
2. Reinstalled workspace — no effect
3. Restarted computer — no effect
4. Ran ClaudeFix v5.3.1 Smart Fix (escalated to Deep Fix, 11GB cache purged) — no effect
5. Enabled Hyper-V (Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All) + reboot — Hyper-V confirmed running (HyperVisorPresent: True), still no effect

Log excerpt (cowork_vm_node.log)

[info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported)
[info] rootfs.vhdx not found, downloading...
[info] Downloading rootfs.vhdx...
[info] [VM] Loading vmClient (TypeScript) module...
[info] [VM] Module loaded successfully

Download starts, service crashes before completing. Loop repeats.

Expected behavior

Cowork workspace starts successfully on Windows 11 Pro 25H2 with Hyper-V enabled.