I have updated kernel to 4.15.0-23-generic and still see this problem:

root@localhost:/sys/block# nvme list
Node             SN                   Model                                    Namespace Usage                      Format           FW Rev
---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
/dev/nvme0n1     CJH0020005EB         HUSMR7616BDP301                          1           1.92  TB /   1.92  TB    512   B +  8 B   KNECD105

root@localhost:/sys/block# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk
├─sda1   8:1    0   476M  0 part /boot
├─sda2   8:2    0  30.8G  0 part [SWAP]
└─sda3   8:3    0 434.6G  0 part /
sdb      8:16   0 931.5G  0 disk
sr0     11:0    1  1024M  0 rom
root@localhost:/sys/block# ls -l /sys/block/
total 0
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop0 -> ../devices/virtual/block/loop0
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop1 -> ../devices/virtual/block/loop1
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop2 -> ../devices/virtual/block/loop2
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop3 -> ../devices/virtual/block/loop3
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop4 -> ../devices/virtual/block/loop4
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop5 -> ../devices/virtual/block/loop5
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop6 -> ../devices/virtual/block/loop6
lrwxrwxrwx 1 root root 0 Jun 25 15:05 loop7 -> ../devices/virtual/block/loop7
lrwxrwxrwx 1 root root 0 Jun 25 15:05 nvme0n1 -> ../devices/pci0000:00/0000:00:01.1/0000:02:00.0/nvme/nvme0/nvme0n1
lrwxrwxrwx 1 root root 0 Jun 25 15:05 sda -> ../devices/pci0000:00/0000:00:1f.2/ata3/host2/target2:0:0/2:0:0:0/block/sda
lrwxrwxrwx 1 root root 0 Jun 25 15:05 sdb -> ../devices/pci0000:00/0000:00:1f.2/ata4/host3/target3:0:0/3:0:0:0/block/sdb
lrwxrwxrwx 1 root root 0 Jun 25 15:05 sr0 -> ../devices/pci0000:00/0000:00:1f.2/ata5/host4/target4:0:0/4:0:0:0/block/sr0
root@localhost:/sys/block# lspci -nn | grep -i Non
02:00.0 Non-Volatile memory controller [0108]: HGST, Inc. Ultrastar SN200 Series NVMe SSD [1c58:0023] (rev 02)
root@localhost:/sys/block# blockdev --getsize64 /dev/nvme0n1
0
root@localhost:/sys/block#

# cat /etc/os-release
NAME="Ubuntu"
VERSION="18.04 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

# dmidecode -t 2
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.6 present.

Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
        Manufacturer: ASUSTeK Computer INC.
        Product Name: P8Z68-V PRO
        Version: Rev 1.xx
        Serial Number: 110104170000300
        Asset Tag: To be filled by O.E.M.
        Features:
                Board is a hosting board
                Board is replaceable
        Location In Chassis: To be filled by O.E.M.
        Chassis Handle: 0x0003
        Type: Motherboard
        Contained Object Handles: 0


4.15.0-23-generic #25-Ubuntu SMP Wed May 23 18:02:16 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux