TL/DR: Is lawful fang bugged or do tharaak hounds in Invaders! have an additional DR component not listed on ddowiki.com?

I noticed today when running Invaders! on my monk/druid that I was not bypassing tharaak hound DR with the aligned fang spell (lawful version) while in winter wolf form. Do the tharaak hounds in Invaders! have an additional DR component or is the lawful version of the aligned fang spell bugged? All I was using was a +8 stunning staff I had crafted (surprising how effective that has continued to be without any further upgrades) as I didn't have any metalline at the time so perhaps there was a metal component I was missing. But according to the DDO wiki, tharaak hounds are supposed to have DR/lawful. Both the good and chaos versions of aligned fang I have used quite frequently (and evil fang in Running with the Devils) and it seems to work in every situation I have needed it both this life and last (both have been druid-based).