This can be caused where you have nominal accounts set to not show on reports, you can find this setting in Financials, Accounts, *select account*, Settings and then you have two options dependant on the report type:
Exclude from Journal reports
Exclude from Record reports
Simply untick the option and save to show on the report.
if this does not solve your issue, then establish when it last balanced and use some of the checks below to narrow down where the problem is:
Export the transaction enquiry screen for the affected period and look for transactions that do not balance
Use Access Office Integration to export nominal turnovers for periods since it last balanced to check for variations.
Query members of the team to establish if they encountered any errors that may have led to the issue.
If this does not resolve your issue, please ask for this to go to your ASC support team and please include details of the difference and results of investigations for reference.