Manage Receipts UI in Accounts Receivable Not showing results using Descriptive Flex Fields.

We have created a Descriptive Flex field with two attributes processed and unprocessed at the receipts creation. If users assigned the processed attribute to a receipt and when the users query the receipt with filter as Processed attribute in Additional information, they are able to view all the receipts which are assigned as processed. However when they query the receipt with the filter as unprocessed or is not blank the UI is not fetching any results. So the DFF's filters will not work if we use them as filters.