When you enroll in Brand Registry even in pending state, you do get access to add A+ Content. When you try to add it says no ASIN is connected to your brand.

Upon opening a case Amazon would tell you things which would go above your head most of the times.

 

Easy Solution: Go to your listing edit, then vital info and edit the brand name. Remove brand name already written and select same brand name from the drop down in brand field. It will connect your Brand with your ASIN and you can now upload A+ Content.

 

Did you face this and were you able to resolve it easily?