All of my available space is disappearing while I am trying to figure out a way to clear space on the drive.
Available Space Disappearing
I have the same problem. Can't open the Xcode 11 archive, because there is not enough free space on the drive. The more GBs I delete, the less free space I have. :-(
In summary I deleted about 30 GB and the free space went down from 9 GB to 7 GB. I suspected, that the TimeMachine Backup might be stored locally until the backup drive is connected. But running (the long overdue) backup, didn't solve anything. I installed the beta on a MacBook Pro, which I don't use much, as we all know, that such kind of problems can always appear when running beta software.
When running "df" in the terminal, I can see, that a second partition was created. It seems like that second partition is autosizing and grabs free space from the partition I can see, as soon as some more free space get available.
Did you find a solution, meanwhile? Or does beta 2 fix the issue and I get my hard disk back?
I think this might be similar to last years beta issues with Time Machine local snapshots to purging to free up space when needed. Definitely need to file a radar for this so they can straighten this out ASAP.