For anyone else having this issue, here's what I did to resolve it:
Clone the "/mnt/cache : Get filesystem data" Item in Zabbix and change every instance of "/mnt/cache" to "/mnt/array" (NOT /mnt/user)
After executing you should get something like this:
{"fsname":"/mnt/array","options":"ro,noatime,user_id=0,group_id=0,default_permissions,allow_other","bytes":{"used":80068584370176,"free":59912069906432,"total":139980654276608,"pused":57.19975005400169,"pfree":42.80024994599831},"fstype":"fuse.shfs","inodes":{"used":277191,"free":13672003897,"total":13672281088,"pused":0.0020273939528882806,"pfree":99.997972606047114}}
You can then clone the "/mnt/cache: Total space" and "/mnt/cache: Used space" and replace "/mnt/cache" with "/mnt/array" and should be good to go.