Did you change markets before the bets were matched? This is a common cause because it cannot monitor the market after a new market has been opened. If you are sure you did not then we cannot tell what happened without seeing a diagnostic log so if it happens again you can send the log file to
admin@gruss-software.co.uk and provide the original bet refs so we can trace it in the log. The file is named BA_Diagnostic.txt and is located in C:\temp\Betting_Assistant_Logs