You may need to configure RRDG to log additional information as explained in https://rpeactual.com/2014/11/26/how-to-enable-dng-debugging-for-document-generation/

In RPE template, you can insert a "JavaScript Code" element. Double click and in the Script expression tab, select the _sessionLogger variable and enter the script. You can generate log entries with one of the following methods:
_sessionLogger.debug(message)
_sessionLogger.info(message)
_sessionLogger.error(message)
_sessionLogger.warn(message)

ex: _sessionLogger.warn("This will be shown in the rpe.log file");