We'd like to help! Wonder if it's a browser issue, could you have your sub try clearing their browser's cache/cookies? Learn more: https://goo.gl/dwzcyo . Also, let us know if they see this across devices and browsers. Keep us posted.
Make sure you select "Notify subscribers" under advanced settings when you publish your videos. Also, your subs can check their account and notification settings: https://goo.gl/PdDKZW . Keep us posted!