The screen does not show up in AppStream 2.0

Overview

The AppStream 2.0 screen (Windows) does not show up in a browser even after signing into the AppStream's UserPool account. I encountered this bug in us-west-2 a few weeks ago, so I set up a new stack and fleet in us-east-1 to make it work.

Today (2022-06-24 PST), my us-west-2's session was expired, so I logged in to the account and encountered the same issue again. From this point, I cannot get into the AppStream's Window screen.

Repro steps

I do not know the reproducible steps, but it seems that AppStream is stuck in this situation after session gets expired.

1. Open the link from the AppStream invitation email.
2. Sign in to the AppStream using the UserPool account.
3. The Windows screen does not show up.

##* Expected behavior:* The application selection page (or the previous session's Windows screen) should appear in a browser.

Actual behavior:

The browser shows a plain dark-navy screen (AppStream's background color) and outputs the following errors in the browser console:

Error: Template (/appstream/views/directives/notification.html) could not be loaded. TypeError: Cannot read properties of undefined (reading 'ownerDocument')
{code: 2, message: 'Display channel is not available.'}

Notes

• OS: macOS Big Sur 11.6.5
• Browsers: Chrome 102.0.5005.115 and Firefox 101.0.1
• Reproducible in an Incognito/Private window. I also removed the cookie/local storage and tried again.