Using Blob field type stops search working on other fields

Running into an apparent issue using BlobType_new to create FieldType.

Scenario:
Creating a schema with two fields, "fullpath" and "title". Using EasyAnalyzer.
Add a couple of entries to the index
Issued a search against the index

Problem: If for fullpath field I use BlobType_new for FieldType, no search match is found. However, if I use either FullTextType_new or StringType_new for the schema FieldType of fullpath, it works fine.

If I do not add fullpath at all, not to schema nor of course with Doc_Store - i.e. just have a single field of title - my scenario works fine (get a search hit).

If I add fullpath to the schema, but not to the doc entries (via Doc_Store), it works fine (get a search hit).

It makes no difference (still get no match) if add fullpath before or after title.

It makes no difference (still get no match) whether I pass true or false as parm to BlobType_new.

In all cases, FieldType for title is fulltext; and it is title that is generating the matches against the search query.