Systemd timer with WakeSystem=true not counting down when system is suspended

I created the transient systemd timer with the command:

systemd-run --collect --unit=alarm-clock --on-active="1h" --timer-property=WakeSystem=true flatpak run io.bassi.Amberol /home/user/Music/test.flac

However despite WakeSystem=true the timer does not count down when the system is suspended. systemctl list-timers --all shows the timer still having almost 1h left.

Transient timer file content
# This is a transient unit file, created programmatically via the systemd API. Do not edit.
[Unit]
Description=/usr/bin/flatpak run io.bassi.Amberol /home/user/Music/test.flac
CollectMode=inactive-or-failed

[Timer]
OnActiveSec=1h
WakeSystem=yes
RemainAfterElapse=no

Any idea on how to debug this?

Edit:
The command also didn’t run after timer elapsed on a waking system… but at least it counted down.
Solved this. The combination of Wayland app and system unit is bad [1] [2]. Newer systemd version will allow WakeSystem with --user.
Though I don’t know why systemd wouldn’t just ask for sudo password instead of failing when certain operations require privilege. (So that I could specify --user and also set wake system.)

Edit2:
The clocks work as expected when queried with Python (suspended 40s in below).

>>> time.clock_gettime(time.CLOCK_MONOTONIC)
494.535988456
>>> time.clock_gettime(time.CLOCK_BOOTTIME)
546.947069797

Turns out it works as expected with shorter duration. Not sure if the problem was a fluke, will test again.

Edit:
Tested again, it seems the computer woke up after 1h as expected, but then waited another 1h to execute the command. I didn’t see the whole process, so I’m still not sure.
I also found a similar problem online.

Edit2:
Nope, same problem on shorter duration as well, the timer doesn’t actually count down until wake, shorter duration just makes the wait shorter.

The dev closed it as non-issue. EDIT: reopened.
Can anyone point out what is incorrect here?
Or have I not gone through the right channel? Should I file a bug report on Fedora Bugzilla instead?

EDIT:
Self reminder of posts to close: 1 2 3 4