Twitch mode disconnects when you glitch a recruit, veteran, and i assume champion deeds aswell (didnt have a champion deed to test it out).
Twitch only disconnects when you try to glitch one as a client, as host it does work.
You can still glitch legend deeds without twitch disconnecting
Glitching refers to the way to change any deed to a custom map and difficulty of your choosing.
Only tried ‘glitching’ them to cataclysm, didnt try any other difficulty, so might be related.