There are a few steps to the answer.

1. Open Disk Util from the system recovery as if you're going to do a factory reset in step 2 from this link: factory reset
2. DO NOT erase the drive, unmount the drive. It's a selection all the way to the right. I'd provide a picture, but you can't take screenshots of the computer in that window. Somehow magically all the space will return
3. Remount the drive and shut down. The undetectable storage will suddenly be free. Restart the computer as is normal.

Should this not work, there is another step you can take before this failsafe.

1. Allow full disk access to terminal in the Security & Privacy portion of the System Preferences (the gear in the rounded rectangle)
2. Install homebrew
3. Install ncdu
4. run ncdu --exclude_firmlinks /

This will do absolutely nothing, but I did do that before the system recovery step and who knows, maybe it's the strong man loosening the jar before the milksop opened it.

There are a few steps to the answer.

1. Open Disk Utility from the macOS Recovery as if you're going to do a factory reset in step 2 from this link: Erase and reinstall macOS
2. DO NOT erase the drive, unmount the drive. It's a selection all the way to the right. I'd provide a picture, but you can't take screenshots of the computer in that window. Somehow magically all the space will return
3. Remount the drive and shut down. The undetectable storage will suddenly be free. Restart the computer as is normal.

Should this not work, there is another step you can take before this failsafe.

1. Allow Full Disk Access to Terminal in the Security & Privacy of System Preferences (the gear in the rounded rectangle).
2. Install: homebrew
3. Install: ncdu
4. Run: ncdu --exclude_firmlinks /

This will do absolutely nothing, but I did do that before the macOS Recovery step and who knows, maybe it's the strong man loosening the jar before the milksop opened it.

There are a few steps to the answer.

1. Open Disk Util from the system recovery as if you're going to do a factory reset in step 2 from this link: factory reset
2. DO NOT erase the drive, unmount the drive. It's a selection all the way to the right. I'd provide a picture, but you can't take screenshots of the computer in that window. Somehow magically all the space will return
3. Remount the drive and shut down. The undetectable storage will suddenly be free. Restart the computer as is normal.

Should this not work, there is another step you can take before this failsafe. 2. Install homebrew 3. Install ncdu

1. Allow full disk access to terminal in the securities and privacy portion of the system preferences (the gear in the rounded rectangle)
2. run ncdu --exclude_firmlinks /

This will do absolutely nothing, but I did do that before the system recovery step and who knows, maybe its' the strong man loosening the jar before the milksop opened it.

There are a few steps to the answer.

1. Open Disk Util from the system recovery as if you're going to do a factory reset in step 2 from this link: factory reset
2. DO NOT erase the drive, unmount the drive. It's a selection all the way to the right. I'd provide a picture, but you can't take screenshots of the computer in that window. Somehow magically all the space will return
3. Remount the drive and shut down. The undetectable storage will suddenly be free. Restart the computer as is normal.

Should this not work, there is another step you can take before this failsafe.

1. Allow full disk access to terminal in the Security & Privacy portion of the System Preferences (the gear in the rounded rectangle)
2. Install homebrew
3. Install ncdu
4. run ncdu --exclude_firmlinks /

This will do absolutely nothing, but I did do that before the system recovery step and who knows, maybe it's the strong man loosening the jar before the milksop opened it.