Oddly, this worked. I’m now getting the reboot notification again.
I’m on Wayland…BTW 
Wayland. But I just tried x11 and that didn’t help.
Further tests showed that I need to enter BOTH a username and an expire time. Either alone doesn’t notify.
I’m ok with entering those, but it’s probably not ideal for new users.
Hard to tell what the reason is.
If you have time and will to do some testing, I’d suggest installing Titan into a virtual machine and see if notifications work there. Note that you may need to install eos-reboot-recommended manually after install.
And if it works in the virtual machine, then comparing packages, settings, etc. between the native and virtual install should reveal the reason.
That suggests there was some problem with the packages or their files.
Anyway, good to hear it is working now. 
Guys, i am having the same issue….did you find a proper solution? Many thanks 
I just installed Titan and eos-reboot-recommended was not installed.
In Titan one needs to install eos-reboot-recommended manually.
Note that not all users think reboot notification is a must have feature, that’s why it was removed from the dependency list of eos-bash-shared.
I installed Titan in a vm and eos-reboot-recommended was installed with it, I didn’t need to install manually. The notification occurred with no action on my part. The conf file didn’t exist until after the update.
I have no idea what else to look at, so I’m resigned to editing the conf. It works that way.
OK, thanks for reporting it works in a VM.
But the old way is useful if that behavior is what you can live with.