I wonder if this is due to the use of systemd. As seen on https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=774082 for Debian.
** Bug watch added: Debian Bug tracker #774082 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=774082 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1573982 Title: LVM boot problem - volumes not activated after upgrade to Xenial To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lvm2/+bug/1573982/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs