Issue with Organizations with multiple Connections

I have a Tennant say (T) . I have configured multiple Organizations (O1, O2, O3…). In one of the Organizations, I have 2 database connections enabled (D1 and D2). In addition I have 2 applications A1 and A2. In each of the applications I have associated respective Connections. So A1 → D1 and A2 → D2. Further I have configured the Organization Tab under each application to (Type of Users = Business, Login Prompt = No Prompt) The Authentication Profile is “Identifier + Password”

With this setting when I use the Universal login with no customization, one of the Database Connections is never recognized. I have to create users in D1 even for Application A2 (which is configured to use D2)

Anything I am doing wrong?