Sandbox sharing doesn't work

I created a project in Neo4j Sandbox, but when I use the invitation feature to share, my colleagues find that the sandbox hangs at the intermediate webpage that says "Neo4j Sandbox Browser: Attempting automatic signin to Neo4j Sandbox"
image.

To test this on the receiving end, I had a friend share a project with me, and then I experienced the same problem, stuck on the intermediate webpage. A user can only view the projects that the user has personally created. Viewing a project that someone else shared doesn't work.