Can't shutdown Linux guest OS with `at` command

Here are three examples of what I did inside the terminal (the third one has sudo): 1.

at now + 5 minutes

(interactively:)

at> shutdown --poweroff now

2.

echo "sbin/shutdown -h now" | at 14:50

3.

echo "/sbin/shutdown -h 16:22" | at now

In every case, I can verify the one-time job is scheduled with the atq command, but the shutdown --show command says "No scheduled shutdown". The system should shutdown at the scheduled time that at runs after sleeping. This is on a CentOS 9 Stream guest virtual machine.  The user is already added to the sudo users group and can initiate the shutdown with a command like shutdown now.  So, with the one-time at job, what’s the difference?