Interactive drop down menu - trying to have selected choice stay selected

I’m trying to make a interactive drop down menu where you have three options to select and when you’ve selected an option after you click back into the drop down menu your selected option should he highlighted with a green bar on the left edge.

Can anyone help to see why when I prototype it everything is working except for the interaction that when I click back into the drop down menu my selected option is not highlighted with the green bar?