The solution that worked for me is to install the version 2.3 from a previous release (I used 17.10).
If you go to the official PPA (https://launchpad.net/~lyx-devel/+archive/ubuntu/release) you will find it. Click on "view package details" and download the packages from the release of your choice. In my case,
lyx_2.3.0-1~artful~ppa1_amd64.deb. I am assuming you have a 64-bit installation.
Remove your current lyx installation using
sudo apt purge lyx && sudo apt autoremove. I recommend installing
apt-get install texlive-generic-extra before proceeding since this package is removed when you uninstall the "old" lyx.
To proceed installing the packages you just donwloaded.
sudo dpkg -i lyx-common_2.3.0-1~artful~ppa1_all.deb && sudo dpkg -i lyx_2.3.0-1~artful~ppa1_amd64.deb. It should work fine.
PS: If it complains about dependencies, do a
sudo apt install -f.