Unable to mount external encrypted disk

Running Kubuntu 17.10 I have an external hard disk of 500GB split into two partitions of equal sizes. One partition is an NTFS partition and the other is an encrypted partition. When I connect the disk to my laptop, Device Notifier shows entries for both partitions separately.

Output of sudo cryptsetup luksDump /dev/sdd1 is:

LUKS header information for /dev/sdd1

Version:        1
Cipher name:    aes
Cipher mode:    xts-plain64
Hash spec:      sha1
Payload offset: 4096
MK bits:        256
MK digest:      40 50 .. ..
MK salt:        b4 cb .. ..
MK iterations:  16500
UUID:           3a2bf693-..

Key Slot 0: ENABLED
        Iterations:             66251
        Salt:                   42 ba .. ..
        Key material offset:    8
        AF stripes:             4000
Key Slot 1: DISABLED

When I try mounting the partition with sudo cryptsetup luksOpen /dev/sdd1 lukslvm, it asks for a password. When I enter a correct password, it produces no error.

After this, ls -lA /dev/mapper shows:

crw------- 1 root root 10, 236 Feb 11 09:52 control
lrwxrwxrwx 1 root root       7 Feb 11 09:52 cryptswap1 -> ../dm-3
lrwxrwxrwx 1 root root       7 Feb 11 09:52 kubuntu--vg-root -> ../dm-1
lrwxrwxrwx 1 root root       7 Feb 11 09:52 kubuntu--vg-swap_1 -> ../dm-2
lrwxrwxrwx 1 root root       7 Feb 13 16:32 lukslvm -> ../dm-4
lrwxrwxrwx 1 root root       7 Feb 11 09:52 sda3_crypt -> ../dm-0

Output of sudo lsblk -f is:

NAME            FSTYPE      LABEL            UUID                                   MOUNTPOINT
sda                                                                                 
├─sda1          vfat                         E551-A70F                              /boot/efi
├─sda2          ext4                         4b..   /boot
└─sda3          crypto_LUKS                  9f..   
  └─sda3_crypt  LVM2_member                  6d.. 
    ├─kubuntu--vg-root
    │           ext4                         29..   /
    └─kubuntu--vg-swap_1
                swap                         6f..   
      └─cryptswap1
                swap                         01..   [SWAP]
sdb                                                                                 
├─sdd1          crypto_LUKS                  3a..   
│ └─lukslvm     ext4        efinso-X53U-back 6a..   
└─sdd2          ntfs        backup           64..                       
sr0                                                       

Output of cryptsetup status lukslvm is:

/dev/mapper/lukslvm is active.
  type:    LUKS1
  cipher:  aes-xts-plain64
  keysize: 256 bits
  device:  /dev/sdd1
  offset:  4096 sectors
  size:    586078488 sectors
  mode:    read/write

The device notifier still shows the volume as not mounted.

When I try to mount it using the device notifier, it produces an error informing me that it can not be mounted.

In Dolphin, when I try to mount it, it produces an error:

An error occurred while accessing 'efinso-X53U-back', the system responded: The requested operation has failed:

Error mounting /dev/dm-4 at /media/sandip/efinso-X53U-back: Command-line mount -t "ext4" -o "uhelper=udisks2,nodev,nosuid" "/dev/dm-4" "/media/sandip/efinso-X53U-back"' exited with non-zero exit status 32: 
  mount: /media/sandip/efinso-X53U-back: can't read superblock on /dev/mapper/lukslvm.

I am able to mount NTFS partition without difficulty.

Also, external hard disks with only one encrypted partition on them load without any error.

What could have gone wrong? How do I set it right?

FWIW, there is a chance that last time I used the encrypted partition, I forgot to eject it.