Firefox With Multi-Account Containers Cannot Login To Subsequent Containers

[influential-eliot]

Incident

The Graph Explorer website does not pass-through login details from pop-ups when using Multi-Account containers.

This is after one or two containers (MACs) have already been logged in some time ago.

To Reproduce

Follow the steps below to reproduce the behavior after having first setup one or two containers with logins:

1. Go to Graph Explorer
2. Click on 'Sign in'
3. Wait for the login.microsoftonline.com pop-up to load
4. Sign in
5. ... nothing happens after it greys out (see Screenshot 1.1 below)

Expected behavior

The login window pops up, I enter the details for the account used in that container, it logs me in and disappears.

Screenshots

Screenshot 1.1

Additional Information

System Information

• Method: Desktop
• OS: Win 11 latest
• Browser: Firefox Nightly
• Version: 126.0a1 (2024-04-08) (64-bit)

Added Context / Information / Thoughts

This occurs with no JS script add-ons / extensions installed, security set to minimum (bad), and tracking cookies even allowed.

When looking at the web-tools console I can see the errors in the attached RAR file, those are all upon page load with the previous sentence in effect.

When tapping login nothing happens in the console or network logs in the web tools.