While evaluating the block of an LTA sock puppet user, I went to Special:AbuseLog and filtered the results by the account's username ("MusikAnimal Devotes life to stop Glapz"). No results are found. See screenshot below:
However when removing all parameters and going through the unfiltered log as it is, I am able to find two logs that should have been returned when I filtered the log by the user name above. See screenshot below:
In this particular example, filtering the AbuseLog by the username returns no results, but viewing the log unfiltered (in fact, I was able to filter by Filter IDs without issue) will show results that should have been present in the previous query.
We might be having issues with inconsistent queries / returns involving this log or possibly the filter when the username is added as a condition.