If you list your volumes by UUID in /etc/fstab instead of by volume name, mountall has no way to know which one is the right one to mount. LVs should always be listed in /etc/fstab by name which is unique; not by UUID, which may not be. All of the historical scripts in Ubuntu for transitioning /etc/fstab to UUID usage explicitly exclude LV names.
So I don't see that there's any bug here that can be fixed in mountall, though this seems like something we should document in the release notes.
If you list your volumes by UUID in /etc/fstab instead of by volume name, mountall has no way to know which one is the right one to mount. LVs should always be listed in /etc/fstab by name which is unique; not by UUID, which may not be. All of the historical scripts in Ubuntu for transitioning /etc/fstab to UUID usage explicitly exclude LV names.
So I don't see that there's any bug here that can be fixed in mountall, though this seems like something we should document in the release notes.