Situation worse with the last 2 updates (plugin compatibility, background tabs)
Please try the Latest Snapshot from https://vivaldi.net/en-US/blogs/teamblog
There are some bugs fixed. Sorry that i dont have all bugfixes in my mind, i apologize if the Snapshot does not help.
Unfortunately, Problem with the Hangouts-Plugin still exist.
I solved the tab issue by disabling "vivaldi://flags#automatic-tab-discarding".
What does not work in Google Hangouts extension?
We have some bugreports and i like to check if it is fixed internally.
Sometimes it works like normal (which will be indicated by a green logo), sometimes it won't. If I click on the hangouts logo I'll get the usual message window, but it will be empty then.
It was working 100% fine two official (not developer) versions ago.
BTW, There is also a different problem with the Google Calendar Plugin. This will require authorizaion and then nothing happens.
Same situation. Windows 7 Professional x64, Vivaldi v.1.0.435.42 () (32-bit).
If I'm signed into Google when launching the browser/enabling the extension, it loads in the glitched mode.
If I disable the extension, sign out, and re-enable it, I get the sign-in prompt in Hangouts. If I sign in, it goes back to the glitched version until I toggle the tray icon, then I can use it. But using it like this makes Vivaldi unstable to the point of crashing in a few minutes (lightweight browsing while streaming music, fine with Hangouts disabled).
I'm at the point where I'm running Chrome in the background just for Hangouts. It's kind of ridiculous.