I am also having the same problem as this person: https://answers.presonus.com/36410/where-is-import-song-data?show=36410#q36410
I cannot find the "Import Song Data" option anywhere in Studio One V4.5 for Mac. I have tried right-clicking on the .song file I want to import in the browse file list. I get the same limited menu as the original poster. I have tried the Song menu on the menu bar. I have tried ctrl+shift+I. My version of Studio One does not seem to include the Import Song Data option anywhere. Is this a bug? Is this feature simply not available on Mac?