If the transactions are shown on the GL Detail Report (which is basically a printed version of the Transactions tab in GL Account Maintenance) and the transactions are included in the Debits/Credits column on the GL Account Maintenance History tab (which should balance to the GL detail report totals for that account), your GL detail and period posting history files are in balance, so it sounds like it would be a report problem. Check that history tab and compare it to your GL Detail Report.
Either way, your reseller or support can probably assist you in resolving this quickly.
