After a while of hunting down the real issue, I figured out that requests that have been denied by the Dynamic IP Restrictions module are not getting logged to the respective site's Advanced Logging file.
In another thread I found out that the Dynamic IP Restrictions module logs at least to default IIS logs so after turning that on again I can see failed requests there (with 401/502 status/substatus codes), but not in the Advanved Logging log file.
In addition, setting the [Logging Only Mode] checkbox to true has the effect that the requests over the limit are being logged to the IIS log with 200/502 but in the Advanced Logging log file they appear as 200/0 which seems like another shortcoming of that module.
Does anyone have any advice on how to set up the Advanced Logging module in a way to correctly capture requests that are or would be denied by the Dynamic IP Restrictions module?