OData filter on Flag (boolean) field causes: An error occurred while processing this request

Hi,

I'm trying to get some pretty simple OData reports going, however I think I may have found a bug in the handling of FLAG (Boolean) custom fields?

Basically if you filter on any Flag type Project custom field (works with built-in fields) then it fails with:

An error occurred while processing this request.

So the following works on a built-in field:

http://project2013test/PWA/_api/ProjectData/Projects?$filter=ProjectCalculationsAreStale%20eq%20true

But this fails:

http://project2013test/PWA/_api/ProjectData/Projects?$filter=TestFlag%20eq%20true

Field name highlighted, everything else is identical.

I've tested this on-premise and on Project Online, can anyone confirm is this a bug or am I missing something?

Martin Laukkanen (Project Server Blog - www.nearbaseline.com/blog)