WKContentRuleListStore fails to compile "Too many rules in JSON array" What's the max?

When trying to compile a rule list via WKContentRuleListStore's -compileContentRuleListForIdentifier:encodedContentRuleList:completionHandler: method I'm getting the following error:

** Rule list compilation failed Too many rules in JSON array.**

The max number of rules allowed in a WKContentRuleList doesn't seem to be documented (or I couldn't find it). Does anyone know what the limit is?

Thanks