With uBlock enabled, Google Hangouts do not work properly (e.g. launching a video call from https://hangouts.google.com/ or the Gmail chat area). I've whitelisted both hangouts.google.com and plus.google.com, and the network request log shows nothing being blocked, and the uBlock icon is grayed out. Specifically, viewing the other person's video does not work (the screen remains black), and it says after 5-10 seconds that the video call has ended and disconnects me.

The only solution I have found is disabling the uBlock extension entirely, after which Hangouts works perfectly. Any ideas?