I'm trying to cast video from sites like YouTube to an LG 49UH620V Smart TV using the "Cast media to device" feature of Microsoft Edge.

LG 49UH620V Smart TV
Firmware Version: 04.30.70 (2-Dec-2016)

DLNADeviceName.lge.com: LG webOS TV UH620V
Date: Fri, 16 Dec 2016 22:03:14 GMT
Server: Linux/i686 UPnP/1,0 DLNADOC/1.50 LGE WebOS TV/Version 0.9

The steps I'm taking to replicate the issue:

1. Open Microsoft Edge.
2. Browse to a video sharing site like YouTube.
3. Start a video playing on YouTube.
4. In Edge, click the three dots and then "Cast media to device".

It looks like it's going to start - but I only get about 3 seconds of video on the LG TV followed by a blank screen. From Edge's point of view - the video is playing and reports it as Connected.

When I do a network capture in Wireshark, it even looks like data is being sent between my computer and Smart TV - although I don't see anything on the TV screen.

I can also see XML transfer between the computer and the Smart TV.

Is there anything else I should be looking at to troubleshoot this. Thanks in advance for any advice.