"You don't have any Pixels." message during Facebook Login for Business

Question

I have a Business Account A, where I have a Dataset setup (which is the what a Pixel is now called) and that Pixel is assigned as an asset to Business Account A's Ad Account.

I have an app under Business Account B which is using Facebook Business Login with scopes ad_management, pages_read_engagement and pages_show_list.

When I try to Facebook Login using Account B's client_id app, and enter credentials for a user which owns Business Account A, I keep seeing the message on the Pixel select screen:

"You don't have any Pixels. To continue, you'll need to create a Pixel using a business portfolio and come back here."

Why is this not seeing the Pixel? The Pixel is collecting data correctly but it doesn't show up during the "connect" process when someone from Business Account A wants to use my service.