Mounted folder not visible over FTP

Hi folks

Have created a new logical volume and mounted it to a directory under Apache's web root.

This is on a Plesk web server by the way.

The folder is accessible over SSH, and if I enable FTP root access, I can see it, and also through Plesk's web UI, but it's not visible to the user when they log in with FTP.

Here is my fstab entry:

/dev/vg_stmacks/lv_stmacks /var/www/vhosts/mydomain.com/httpdocs/members auto defaults 0 0

The owner of the mount target (members) is correct, and directory properties on the target also correct.

How can I ensure this user can view the mounted folder over FTP?

Many thanks for any guidance.