You can check 'indexed content' tab, to see what your search index contain. By default, in transformation is used 'Title', 'Content' etc. If you removed that from your page types, maybe you can't match any of this fields and because of that you got empty transformation. You can check this by going on the page types -> your_page_type-> search fields and check this fields.
Also you can use Lucene tool to check if everything is okay with your indexer.