I read the thread at How to compact VirtualBox's VDI file size? but those solutions didn't work for me. Here's what I tried:
I had used CloneVDI successfully for years without a problem, but it suddenly fails to compact at all. I have (and have always had) 2 partitions on the guest OS (C: 42gb, F: 20gb). After deleting a large database file and shrinking the F: partition from 45gb to 20gb using MiniTool Partition Wizard (and eliminated empty space gaps between the partitions), I ran CloneVDI with the Compact option selected and there was no change in size (it should have reduced the size from 82gb to a maximum size of 62 (the sum of both partition sizes). I also tried sdelete C: -z and sdelete F: -z followed by vboxmanage modifymedium <path to .vdi> --compact with no effect (snapshots had been removed prior to running).
Never ran defrag in the past and can't on either partition since the .vdi is on an SSD (and is marked in Vbox settings as an SSD).
Am I missing something?