I had the same problem with the '/mnt/array' mount on Zabbix. I did a 'df -h' and see that the filesystem is 'shfs',
nas:/var/lib/zabbix$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/loop2 60G 23G 37G 39% /
tmpfs 64M 0 64M 0% /dev
shm 64M 0 64M 0% /dev/shm
/dev/sdc1 466G 75G 391G 17% /mnt/cache
shfs 73T 11T 63T 14% /mnt/array
/dev/loop2 60G 23G 37G 39% /etc/hosts
tmpfs 128M 2.1M 126M 2% /run/docker.sock
so, in Zabbix I clone all items for the '/mnt/cache' (which works), as suggested by @epiphanyplx, replacing 'cache' for 'array' and 'btrfs' for 'shfs', and it seems to work.
I don't know on others versions, but in Unraid 7.0, '/mnt/user' is a 'shfs' filesystem.
Hope it helps.