Ron, that would typically be due to one of two things. Either the log being used for debugging doesn't contain sufficient information for log-based debugging, which would occur because the logging levels used during process execution were insufficient, or there's a bug in how IC is parsing that log into executed stack frames. My guess is that it's the former just because I haven't heard about that type of issue in a long while (years), but that absolutely doesn't mean there's not such a bug.
The first line of the log should show the logging levels. Can you share those so we can determine whether or not that's a contributor?
Regards,
Scott Wells