webRequest.onCompleted event stops working until after restarting

I’ve been getting bug reports of our extension acting weird when a user is upgraded to a new version. I’ve been able to isolate it to a problem with the webRequest.onComplete event.

The problem is that the event stops firing until the browser has been restarted. After restarting the event works as expected.

Any idea why this happens or do I need to tell users to restart after an upgrade?

Here’s where I’m using that event:

Please file a bug report for this. Attaching a test case would help figure this out faster.