Folks, I just wanted to update you on new findings about this issue. I had a message open with SAP and they suggested to upgrade to 55. After upgrading to 55, the disk space utilization is now refreshing automatically without having to restart HANA! I did a test where I copied a bunch of data from one table to another and for a few minutes the disk size on the new copy was inflated but then automatically shrunk to expected size.
-Patrick