Reclaim free space from UTM VM

I'm running the UTM VM appliance on ESXi 5.1, and there's a mismatch regarding the disk usage between the UTM and ESXi. Specifically, the UTM claims to be using 7.1 GB total, while ESXi is reporting that it is using 32.7 GB. Note that the virtual disk is thin provisioned, with a maximum allocation of 50 GB.

I've included captures from the UTM and ESXi below.

Any suggestions on how I can correct this? Thanks for your help.

/root # df -h --total
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda6       5.2G  2.3G  2.7G  47% /
udev            501M   72K  501M   1% /dev
tmpfs           501M     0  501M   0% /dev/shm
/dev/sda1       331M   14M  300M   5% /boot
/dev/sda5        17G  4.1G   12G  27% /var/storage
/dev/sda7        22G  678M   20G   4% /var/log
/dev/sda8       1.3G   17M  1.2G   2% /tmp
tmpfs           501M   20K  501M   1% /var/sec/chroot-httpd/dev/shm
tmpfs           501M   80K  501M   1% /var/storage/chroot-reverseproxy/dev/shm
tmpfs           501M   80K  501M   1% /var/storage/chroot-smtp/tmp/ram
total            47G  7.1G   38G  16%

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