Why is the Package Manager menu item disappearing?

I'm trying to setup a git submodule and import it as package but I couldn't find the Package Manager. There are no compile errors. How can I fix this?

 

• What version of Unity are your using?
• Do you have packages installed that are not Package Manager UI?
• Is this a new project?
  

 

• 2019.1.0f2
• Yes
• Yes

 

Try this (possible) fix: https://forum.unity.com/threads/missing-package-manager-case-possible-fix.660460/

 

I've had this exact problem occur. I found that another package was out of date and causing a dependency error. This created the issue of the subsequent packages (including the package manager features) to not be loaded.