Thanks so much!
The menu disappears when you double-click outside of it after closing the actual menus. (Kind of like how VTube Studio does the menu show/hide.) Then re-appears if you double-click again. I'll make sure I have that listed on the download page somewhere obvious, probably under Controls if I don't have it already.
I'm not sure why Twitch wouldn't authenticate. I'll make sure it's working on my end still. Does putting in your channel ID and hitting authenticate open up a webpage that asks you to agree to permissions? (It's supposed to.) Edit// Can confirm that it authenticates for me, so I'm not sure what the issue is.