Why is the BSR zero?
This occurs when either
The listing has not seen any sales
The variation does not have a BSR
Why is sales per month zero?
Sales per month can be zero for a few reason. Typically
The BSR is high enough that the calculated sales per month is actually zero
The product does not have a top level category (typically seen with high BSR products)
The BSR is 0
Why is the average BSR or average price 0?
The average values can come back empty or 0 if we do not have a full 30 days of historical data. We don't ever return impartial historical data points.