Claude in Chrome extension not connecting after fresh install and full restart

Claude in Chrome extension will not connect, even after following all standard troubleshooting steps.

Steps already taken:

Installed the extension fresh via https://claude.ai/chrome ("Add to Chrome" confirmed)
Verified in chrome://extensions that the extension is listed and enabled
Confirmed logged into claude.ai in the extension with the same account used in the Claude session
Fully restarted Chrome (ended all chrome.exe processes via Task Manager, then relaunched)

Expected: tabs_context_mcp (and other browser automation calls) should connect to the extension.

Actual: Every call still returns:
Browser extension is not connected. Please ensure the Claude browser extension is installed and running...

This was retried multiple times over several minutes with no change.

OS: Windows
Browser: Google Chrome