index an attribute makes it unusable in a filter

We have a custom string attribute in our ldap schema that tracks the status of the user's account. If the attribute is indexed any search query which filters on that specific attribute fails to return any results. If I remove the index on that attribute then everything runs fine. While this is not a show stopper, it would still be nice to index this particular attribute since it is used in filters very often.

I was wondering if someone has noticed similar behavior and what the solution might be. We have other custom attributes are being indexed and functioning correctly.

Thanks in advance -sud