slip through the cracks
To go unnoticed or undealt with; to be unintentionally neglected or ignored, especially in a corporate, political, or social system. With other issues like drug addiction and unemployment taking priority for the government, the welfare of children in the foster system very often slips through the cracks. We were all so busy drawing up the contracts for this new deal that the appreciation dinner we'd promised to our interns simply slipped through the cracks.