I have also seen this on a couple of SSD-only systems. I think the problem is that the random number generator takes about two minutes to initialize, long enough for systemd to give up on these processes. Unbound is similar, but there unit file keeps trying until the random numbers are available.
>From the log: May 5 10:19:02 ano2 kernel: [ 126.436729] random: crng init done Pressing the keyboard a few times (thus providing entropy) will allow the boot to continue. This definitely seems to be a kernel problem. Arne
