It seems that it's not the issue from Station's side. I could manage it to work only this way

Hello Adil, we don't officially support Vivaldi, but have you tried setting the shortcut yourself? Sometimes browsers already use the shortcut we set and there can be conflicts.

It's usually inside the browser Extensions settings > Keyboard. Here's an article about how to do it in Chrome if that can help 👉 http://faq2.stationhq.com/en/articles/4263516-how-can-i-change-my-keyboard-shortcut-to-open-station