I don't know why this is happening again but it happened in either the F21 or F22 time frame. I've installed Fedora-Live-Workstation-x86_64-23_Beta-TC4.iso and then dnf upgraded it which includes a new kernel. Yet the old kernel is being used by default.
https://drive.google.com/open?id=0B_2Asp8DGjJ9a0VpejBuVmktSWs
# grub2-editenv list saved_entry=Fedora (4.2.0-1.fc23.x86_64) 23 (Workstation Edition)
That's wrong. I don't know why it's set to that because anaconda program.log shows
10:33:15,396 INFO program: Running... grub2-set-default 0
Anyway this is probably a blocker.