You will not see your changes you made in the dev mode until you build the package and put the package in your community folder.
So, once you placed your POIs, build the package in the inspector window.
Then in MyFSProjects, go to your new mod folder, and copy the folder in ‘Packages’ to your community folder.
I think the creation of personal POIs (ie not meant to share with anyone) should be made easier without needing to go into the SDK. You could vote for this here: Add custom POI