When looking at paginated saved search results, it may work on some pages and then not others due to the root cause. Since it's a transaction saved search, there may be several issues. Are you restricting by a particular transaction type? I would try that. Have you set mainline to N in the criteria (mainline records won't have an item in them I believe, only the item records). Also, you mentioned it's a currency formula. As a test, I'd try to use a numeric formula. You could also add {customitemdatefield} IS NOT NULL AND to your formula (after CASE WHEN).