You need to give us more information.  What method did you use, exactly, as a subobject selection filter when it worked before?  Filtering can be done in the (ssget) AutoLisp function, or in the FILTER or QSELECT commands, but as far as I know, none of those can find nested objects, only top-level objects.  So we would need to know how you were doing it, in order to come up with any ideas about why it no longer works.