Maybe the UUID is the wrong one? Note that if you change the fstab, you need also run: systemctl daemon-reload, so that the “fstab-converter” catch your changes.
Let’s say, you mount sdb2 manually without fstab. Systemd knows that it is mounted. When adding a fstab entry and run mount -a, even if unmounting before, systemd remembers your old mount not the one from fstab. Therefore, you need to reload the daemon.
Thanks. I did double check the UUID, and copied and pasted it. I also did the daemon-reload each time, but did not document it in my original post.
Your explanation of the process explanation helped make it clear why I was doing it.
Just to be sure, I retested, and the results are still the same. The drive mounts when I do a mount -a after a daemon-reload, and after a reboot, the logs say the partition is mounted, but nothing shows when a do an ls -al.