Are you sure that the standard categories are overriding? It's more likely that the WBRS engine is allowing the content since it takes precedence of the standard categories.
Custom category allows have highest preference and will override everything.
Make sure that you disable WBRS in your rules that you wish to us whitelisting on.
If that still doesn't do the trick, let's take a look at the access logs to determine what action is triggering and why.
To grep the access logs for this entry, run the following from the CLI:
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1. Grep
2. Enter the number of the log you wish to grep: 1 (for accesslogs)
3. Enter the regular expression to grep: .*
4. Do you want this search to be case insensitive?: Y
5. Do you want to paginate the output?: N
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