Read your log:
Apr 18 19:17:00 Tower unassigned.devices: Adding disk '/dev/sdk1'...
Apr 18 19:17:00 Tower unassigned.devices: Mount drive command: /sbin/mount -t ntfs -o auto,async,noatime,nodiratime,nodev,nosuid,umask=000 '/dev/sdk1' '/mnt/disks/Network_Storage_HDD'
Apr 18 19:17:01 Tower ntfs-3g[27708]: Version 2017.3.23 integrated FUSE 27
Apr 18 19:17:01 Tower ntfs-3g[27708]: Mounted /dev/sdk1 (Read-Only, label "Network Storage HDD", NTFS 3.1)
Apr 18 19:17:01 Tower ntfs-3g[27708]: Cmdline options: rw,noatime,nodiratime,nodev,nosuid,umask=000
Apr 18 19:17:01 Tower ntfs-3g[27708]: Mount options: rw,nodiratime,nodev,nosuid,allow_other,nonempty,noatime,ro,default_permissions,fsname=/dev/sdk1,blkdev,blksize=4096
Apr 18 19:17:01 Tower ntfs-3g[27708]: Global ownership and permissions enforced, configuration type 1
Apr 18 19:17:01 Tower unassigned.devices: Mount error: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Falling back to read-only mount because the NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting.)
The last line indicates the problem.