Apple - Missing disk space on macOS

It seems like the two most likely candidates are a mounted (shared) disk overwriting a location with large files, hiding them from your view, or large (or many many small) files that are held open by a process, but have already been deleted. If you haven't rebooted the computer yet, that's worth a shot, but also booting into recovery mode and running first aid on the disk might help. lsof | grep deleted might also reveal interesting information, if lsof is available on OSX (I assume it is, but I've never looked)

I've also noticed in my own use that if I use a tool like DiskInventory or Grand Perspective and there are other users on the system, they won't show the size of other users files if I don't have read access to them (reasonably so). If you have other users on your system, they may have large files in their home directory you're not seeing.

I finally reinstalled the system after erasing the volume. With a Time Machine backup it was more or less a smooth experience. Now I have 170G of free space.

tl;dr:

• Missing disk space can be related to a broken filesystem
• APFS tooling is currently really bad, you probably need to erase the volume and reinstall to fix any filesystem problem

Commands given below resolved the issue for me. Listed and deleted local snapshot and it freed 230 GB on my machine.In step 2, you enter the date/time received from step 1.

$ tmutil listlocalsnapshots com.apple.TimeMachine.2019-01-28-143406   

$ tmutil deletelocalsnapshots 2019-01-28-143406  

$ tmutil listlocalsnapshots /

Make sure it shows no file