I have a VM runiing CentOS in it.
After deleting some files with several GB in size within the VM i shut it down and selected "Edit virtual machine settings" - "Hard Disk" - "Compact" to compact the disk and save space on the host.
This doesnt work. There is no progress bar appearing - it says directly "The disk was successfully compacted". But it wasnt. The current size did not change.
Same happens with "Defragment".