I have the same issue. Usually, if it's the first time I open the page I can scan the QR code to sign in. But after I've logged in, and if I were to restart the computer or restart the browser, in most of the other browsers I'll already be logged in and can view my chats. But often in Orion, it would take forever to load or get stuck. To fix this I usually, unpin/close/suspend the Whatsapp tab, clear cache etc, then when I open a new window with whatsapp it works. So I'm not sure what the exact root cause is. You probably have to use Whatsapp Web regularly to notice this happening.
This issue has happened since I first tried orion a few months ago.