Не удалось установить гостевые дополнения VirtualBox на Ubuntu 18.04.2 LTS с HWE - почему?

Недавно я установил HWE на своем LTS Ubuntu 18.04.2, работающем в VirtualBox. Это была чистая установка без любого PPAs и без сторонних репозиториев. Некоторая информация ниже:

$ head -n2 /etc/apt/sources.list
#deb cdrom:[Ubuntu-MATE 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426)]/ bionic main multiverse restricted universe

$ hwe-support-status
Your Hardware Enablement Stack (HWE) is supported until April 2023.

$ dpkg -l | grep hwe
ii  linux-generic-hwe-18.04                 4.18.0.15.65                            amd64        Complete Generic Linux kernel and headers
ii  linux-headers-generic-hwe-18.04         4.18.0.15.65                            amd64        Generic Linux kernel headers
ii  linux-image-generic-hwe-18.04           4.18.0.15.65                            amd64        Generic Linux kernel image
ii  xserver-xorg-core-hwe-18.04             2:1.20.1-3ubuntu2.1~18.04.1             amd64        Xorg X server - core server
ii  xserver-xorg-hwe-18.04                  1:7.7+19ubuntu8~18.04.2                 amd64        X.Org X server
ii  xserver-xorg-input-all-hwe-18.04        1:7.7+19ubuntu8~18.04.2                 amd64        X.Org X server -- input driver metapackage
ii  xserver-xorg-input-libinput-hwe-18.04   0.28.1-1~18.04.1                        amd64        X.Org X server -- libinput input driver
ii  xserver-xorg-legacy-hwe-18.04           2:1.20.1-3ubuntu2.1~18.04.1             amd64        setuid root Xorg server wrapper
ii  xserver-xorg-video-all-hwe-18.04        1:7.7+19ubuntu8~18.04.2                 amd64        X.Org X server -- output driver metapackage
ii  xserver-xorg-video-amdgpu-hwe-18.04     18.1.0-1~18.04.1                        amd64        X.Org X server -- AMDGPU display driver
ii  xserver-xorg-video-ati-hwe-18.04        1:18.1.0-1~18.04.1                      amd64        X.Org X server -- AMD/ATI display driver wrapper
ii  xserver-xorg-video-fbdev-hwe-18.04      1:0.5.0-1ubuntu1~18.04.1                amd64        X.Org X server -- fbdev display driver
ii  xserver-xorg-video-intel-hwe-18.04      2:2.99.917+git20171229-1ubuntu1~18.04.1 amd64        X.Org X server -- Intel i8xx, i9xx display driver
ii  xserver-xorg-video-nouveau-hwe-18.04    1:1.0.15-3~18.04.1                      amd64        X.Org X server -- Nouveau display driver
ii  xserver-xorg-video-qxl-hwe-18.04        0.1.5-2build2~18.04.1                   amd64        X.Org X server -- QXL display driver
ii  xserver-xorg-video-radeon-hwe-18.04     1:18.1.0-1~18.04.1                      amd64        X.Org X server -- AMD/ATI Radeon display driver
ii  xserver-xorg-video-vesa-hwe-18.04       1:2.4.0-1~18.04.1                       amd64        X.Org X server -- VESA display driver
ii  xserver-xorg-video-vmware-hwe-18.04     1:13.3.0-2build1~18.04.1                amd64        X.Org X server -- VMware display driver

$ uname -r
4.18.0-15-generic

Перед установкой HWE я установил virtualbox-guest-x11, но теперь это удалено. Кроме того, я не могу установить его снова:

$ sudo apt install virtualbox-guest-x11
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 virtualbox-guest-x11 : Depends: xorg-video-abi-23
                        Depends: xserver-xorg-core (>= 2:1.18.99.901)
E: Unable to correct problems, you have held broken packages.

и HWE-именованный также:

$ sudo apt install virtualbox-guest-x11-hwe 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 virtualbox-guest-x11-hwe : Depends: xorg-video-abi-23
                            Depends: xserver-xorg-core (>= 2:1.18.99.901)
E: Unable to correct problems, you have held broken packages.

Что мне делать?