When you view the AR transactions for one of these customers, what is the Current Balance of the RETAIN cash or the invoice? If they are non-zero amounts, then they will never get cleared to history. Only transactions with a current amount equal to zero will get cleared to history. This situation usually occurs when a cash deposit is first posted, followed later on by an invoice that has a different document number than what was initially reserved by the Cash in a UP detail (if used).

You have 2 choices for dealing with these transactions that should be matched together but are not yet.

1) Create a cash entry in AR for the customer. Leave the entry amount as 0.00. Apply it to the RETAIN cash entry and also the outstanding invoice. When you post this 0.00 cash entry, all the transactions are considered matched and current amounts become zero. No GL activity will be generated by this entry.

2) Use the Create Write-off Batch function in AR to automatically deal with customers that have unmatched transactions that net to 0.00 and should be matched together. Do this from the Maintenance menu. Either select the customer in question, or choose to write off 'Balances' in the range of 0.00 to 0.00. Whatever you do, this will create an Adjustment batch that when posted, will set the Current amount of all transactions for the customer(s) to 0.00. All GL amounts will net to zero.

The first option gives you more control over what is happening and is typically best used when there are only a couple of customers to deal with, or if the customer balance is not exactly 0.00 but have invoice/cash transactions that should be matched but are not.

The second option is much quicker to use when there are a number of customers in this scenario, or even other customers that you are not aware of that have outstanding transactions that all net to zero. You can't use this if the customer has a non-zero balance as they will be skipped by the Write-off batch generation process.