please open a Case at PTC Support and show them that preview action used during a rule definition is able to find mfg item and that this information is lost when rule definition is finished and layer definition is saved.
this is another example of things don't work properly but we won't fix it. I think this couldn't be to hard to fix and would save our users a lot of annoying work every day. At the moment they have to designate those features manually to predefined layers.