Custom Entity Not Displaying in Custom Model-Driven App Navigation

In my sandbox environment I have created a new model-driven app which has its own solution. I've also created a custom entity and added it to the solution, along with Accounts and Contacts. When I load my app I see Accounts and Contacts in the navigation area on the left. Then I've edited my site map to include the custom entity and published. When I load my app now I still only see Accounts and Contacts. I even went as far as to remove contacts from the site map. After that my navigation still showed Accounts and Contacts.

What steps am I missing or messing up in the addition of this custom entity?

Just make sure you are doing this troubleshooting steps.

1. Save/Publish the Sitemap and Model driven app. Ans also "Publish all customizations" to avoid any left overs
2. Verify if you are checking/editing the same App and its respective sitemap
3. Sitemap item (subarea) can be hidden using particular privilege and tick-off that it is not that case
4. If deploying to another environment, add the app and sitemap to the deploying solution