Yes, that time it wasn't going through and that is right. What has been the case is that the inventory was showing up online on the United website but was not available.
This time it was more of planning where I arranged a proper US address. I confirmed with United CC over a call for award availability, initially, they were telling me No, and then when I told them that I confirmed with Ethiopian Airlines with the specific flight number about the award availability, customer care said, to hold on and then they confirm that yes the Inventory was available.
So those who are entering The us Address for billing and yet the transaction is not going through is because of the Award availability.
This time I prepped well.
1) confirmed with the Airline I was flying( Ethiopian)
2) Called Customer Care of United.
3) Transferred My 1Lac point to United.
4) Arranged Amex Card from India( I heard it works); Two, Had a proper US address;
5) Prepared to call customer care of United if this time transaction didn't go through and would have booked there.