I've done everything short of rebooting the system

Which would work. Otherwise you must either:

• Explicitly start the timer: systemctl start foobar.timer
• Or restart the timer target: systemctl restart timers.target

systemctl status will now show foobar.timer as "active (waiting)".

I've done everything short of rebooting the system

Which would work. Otherwise you must either:

• Explicitly start the timer: systemctl start foobar.timer
• Or restart the timer target: systemctl restart timers.target

systemctl status will now show foobar.timer as "active (waiting)".

As per don_crissti's comment, enabling the timer with --now also works:

systemctl enable --now foobar.timer

I've done everything short of rebooting the system

Which would work. Otherwise you must either:

• Explicitly start the timer: systemctl start foobar.timer
• Or restart the timer targert: systemctl restart timers.target

systemctl status will now show foobar.timer as "active (waiting)".

I've done everything short of rebooting the system

Which would work. Otherwise you must either:

• Explicitly start the timer: systemctl start foobar.timer
• Or restart the timer target: systemctl restart timers.target

systemctl status will now show foobar.timer as "active (waiting)".