Did you sign into Dtube with Private Key because there seem to be problems whenever clicking "Login With SteemConnect" button... if you gone with Private Key sign-in route make sure to click the "Remember me" button so you don't end up logging out.
Here's a link to DTube FAQ (In case you don't know your Private Key:
https://about.d.tube/#faq1
In case you still have problems there's an Alt-livestream connected to Steemit called:
https://www.vimm.tv
As bonus there's also other useful tools such as OBS/XSplit alternative broadcast software and "multi-streaming platform that helps you stream to more than 30+ channels at once.":
https://streamlabs.com
https://restream.io
Oh yeah so far both Opera and Brave browser works for me so far to a point I can see the stream key.