I have been struggling with some really weird issues with Bobo suddenly not finding facet results based on SimpleFacetHandler.

Finally I realized that a regression bug was introduced recently in the constructor:

public SimpleFacetHandler(String name,String indexFieldName,TermListFactory termListFactory)
{
   this(name,name,termListFactory,null);
}

should be public SimpleFacetHandler(String name,String indexFieldName,TermListFactory termListFactory) { this(name,indexFieldName,termListFactory,null); }