To close this thread...
As far as we can determine, this data had a Period End run on March 6, and then a Year End dated February 29. This meant that transactions are in history that would not have been moved if the Period End had been run on February 29.
This report uses the Last Period End date in the company profile to determine whether the report being requested is back dated or not. Since the Year End date matches the Report date, the transactions in history are not being inspected (and are therefore missed in the report).
If it is critical to get an ATB to tie back to Ledger, then you can change the Last Period End date in the AR company profile using GridView Read-Write, or run a Period End dated March 1. Both of these actions will cause the ATB report to inspect the transactions that have been moved to History.
As mentioned previously, all the accounting entries are correct, and it turned out that this had nothing to do with the February 29th date. It would happen regardless of the number of days in the month.
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Andrew Bates