I'm using CiviCRM to (in part) manage a large group of translation volunteers for our organisation. I've got everything set up quite nicely, using custom fields and groups to help our staff manage translators able to work in different languages, know whether they have already had a translation requested, etc. I've got the various smart groups set up as menu items, so other staff can quickly see which translators are available in which languages, which are occupied, etc.
We have a custom date field for "date finished last translation", so staff know if a translator has recently finished a translation. One thing I'd like that I can't work out is how to list this date field in the smart group search. At the moment that search displays their name, email, and their language. However, whenever I add the "date finished last translation" field as "is not empty" or "is not null" it returns no contacts, even though I know there are contacts who have that field completed. If we get it working, staff will be able to easily see who has most recently completed a translation, so not ask them again.