Have you checked if you've selected '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.
Thanks for the screenshot. "Notify subscribers" is under the "Distribution option", which is checked. However, if your subs are still not receiving notifications, you could ask them to troubleshoot the problem using this link: https://goo.gl/6zv3yX . Let us know.