While working a issues that required opening a case with Premier Support I was given a link to a great resource to use while troubleshooting distribution points and content distribution issues. If you do not know about it take moment to review and save it for when you need it. https://support.microsoft.com/en-us/help/4000401/content-distribution-in-mcm
Special thanks to Vinay Pamnani, Senior Support Escalation Engineer with Microsoft. He shared the link and has published several tools that are part of many Configuration Manager Administrators tool belt.