ODataQueryOptions.Filter uses Odata filters. These do not translate through to MongoDB syntax. This prevents MongoDB from being the backing store for an OData endpoint without plenty of extra work.

Ex: StartsWith is enabled through a regular Queryable/Where Expression has call syntax Syntax ".Call $e.Name.StartsWith(\"X\")". From the OData query, the RawFilter bceomes "startswith(Name,'MPMD')" The MongoDB Driver doesn't understand that format.

More examples of queries which don't translate: http://www.odata.org/documentation/odata-version-2-0/uri-conventions/