I do think the "works half the time" behavior of grub safe boot is coming into play. It's not exactly half the time but whenever I get a hang, I definitely get the grub screen afterward. Occasionally I get the grub screen more than once in a row though.
I downgraded libplymouth2 plymouth plymouth-theme-ubuntu-logo plymouth- theme-ubuntu-text and plymouth-label (the only installed *plymouth* packages). It still hangs about half the time. Probably not relevant, but reported here for completeness. I got these warnings at the end of the downgrade. cryptsetup: WARNING: failed to detect canonical device of /dev/sda3 cryptsetup: WARNING: could not determine root device from /etc/fstab (FWIW, I re-updated to keep the number of variables low). ** Changed in: plymouth (Ubuntu) Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1016170 Title: No login screen unless "quiet splash" removed from boot line To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/plymouth/+bug/1016170/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs