Found a nasty little bug in LVM2 when installing it as a dependency of gparted, installed 'as is' there seems to be a conflict with the newer version and udev that will prevent booting see this:
https://bugs.gentoo.org/show_bug.cgi?id=409921
And this:
https://forums.gentoo.org/viewtopic-p-6999564.html

If you have already installed LVM2 and configured it your self you may not have come across this but in the config file in /etc/lvm/lvm.conf this line:causes the boot failure ( about line 527 ), simply change it to locking_dir = "/dev/shm/lvm" to fix the problem, you can also use a sed like so:I assume this fails as /var/lock/lvm is not writable at boot time.

/var/lock is symlink to /run/lock and /run is on tmpfs, so it should be writable, given that /run is mounted early at boot.

Not on my system it's not.

Whoops! mucked up a symlink, don't know how that happened!