How to enable deduplication?

I’m currently testing out urbackup and struggle a bit to enable deduplication.

As a test, I did 3 images of a Windows laptop back to back. The backed up drive got 30gb of data, each backup (cVHD) is 15gb in size. I expected to see actual drive usage of <20gb for all three backups, since no meaningful amount of data changed since the last backup.

However, it uses the “full” 45gb as seen below.

UrBackup server is running on a Debian VM and backs-up to a ZFS accessed via SMB (going to switch to NFS). I know that ZFS supports block-level-deduplication, but since the same Pool gets used as NAS, I don’t want to enable it there.

Quick side question, how do I browse an image in the web interface?
I’ve found this blog post, but it doesn’t show the “Mount Image” button for me.

I’ve now made the switch to NFS to make sure there are no problems with SMBs mfsymlinks. Sadly, deduplication still doesn’t seem to work. Since I’m also unable to find any settings related to deduplication, I’m wondering if I’m doing something wrong here.