CMIS contains for folders?

I can't seem to return any results with the following query (testing through Workbench) :
SELECT * FROM cmis:folder where CONTAINS('Contracts')
That should return at least one folder - including the sample app folders. My intent is to search any indexed properties of cm:folder, of course.

This query returns one of the sample folders:
SELECT * FROM cmis:folder where cmis:name like '%Contracts%'

So why doesn't the CONTAINS clause work for folders??? It works fine for documents. I have tried various searches, but using CONTAINS with cmis:folder never returns any results.

Thanks for any insight.
-AJ