Server Settings - Disk Quota

The GUI 'Disk Quota Settings' isn't working for me in CWP7pro.

The page states:

You should setup quota for the /home partition.
UUID=aa517e7e-442d-4fbf-b555-a1031283d354 /home ext4 defaults 1 2

I then enter "/home" in the "Quota Partition:" text entry field; and select "Save Changes";
It responds with "Data Updated!" but no changes are made.

I can't find any errors in logs etc.

I can of course set it up manually, yet would like to understand why it may not be working via the GUI - and the Wiki suggests the manual option is deprecated with this GUI option. 

I have a second drive (ext4) mounted at the /home partition if that makes a difference:

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        16G  5.8G  9.2G  39% /
devtmpfs        3.8G     0  3.8G   0% /dev
tmpfs           3.8G     0  3.8G   0% /dev/shm
tmpfs           3.8G  225M  3.6G   6% /run
tmpfs           3.8G     0  3.8G   0% /sys/fs/cgroup
/dev/sdb1        63G  3.8G   56G   7% /home
/dev/sda1       976M  130M  780M  15% /boot
tmpfs           764M     0  764M   0% /run/user/0

Thanks.