Multiple people have been reporting that on Orion Browser (Built on WebKit, supporting both Firefox and Chrome extensions) by Kagi, Proton Pass suffers from lag and intermittently tells one that the vault is empty. Since Orion is one of the most popular privacy-focused Browsers right now, I hope Proton will put some effort into improving compatibility.

Edit: Currently, the Firefox extension works best with Orion, the Chrome extension is unusable (login fails for me, it cannot communicate with the extension)