Garageband still taking up space in High Sierra
These are all the GarageBand folders...make sure they are all empty.
Also, quit and restart Storage Management after you have cleared those folders to see the changes or even a reboot, might help sort some other things out. Hope this helps...


/Applications/GarageBand.app
/Library/Application Support/Garageband
/Library/Application Support/Logic
/Library/Audio
~/Library/Application Support/Garageband
~/Library/Application Support/Audio