If you look at the log message, it will tell you exactly why the traffic was allowed: There was an "Internal System Error."
There is a fail open/close switch for that situation.
In this case, that setting is allow.
When you go find the rule that allowed the traffic, it doesn't exist.
Of course, you can set it to fail close if you prefer.
Here's where to make that change:
This begs the question: why the internal system error?
That will likely require a TAC case to troubleshoot.
"Internal System Error occurred" log in SmartView Tracker while trying to categorize resource