Bill Problem (Cant update or delete)

Bill Problem (Cant update or delete)

While recording a Purchase Transaction manually under (Purchases => Bills) we have 20 entries in single bill. We purchased 20 SKUs in single Invoice. But we are facing these issues.

Problem Scenario
1) While recording this transaction manually Zoho Books didnt allowed to enter not more than 5 entries. 
2) So we tried to do using CSV Import but getting error that Invoice no. already exists.
3) Then we tried to delete this Bill and got this error. "You do not have sufficient stock to create out-transactions for the item <ItemName>. Please restock the item and try again."

Error while deleting the Bill.