I have chased this and now have a solution.
The problem was that when I suspended the system it immediately resumed. Lots og Googling and many a dead end but I discovered that the issue was to do with XHC [I didn't have XHCI]. Looking at /proc/acpi/wakeup I had:
I disabled it:
This allowed suspend to work BUT the remote & USB keyboard didn't cause a resume and I had to physically press the power button. Both my remote and keyboard are USB connected. A bit more digging and I started to question the setting of EHC1 & EHC2, both were disabled in /proc/acpi/wakeup
I enabled both:
Suspend worked as did resume when pressing a remote control key or USB keyboard key. I refined this to discover that only EHC1 effected my remote & USB keyboard . Of course my changed settings were lost after a reboot.
Time to systemd.
I created a service wakeControl.service in .config/systemd:
[Unit]
Description=wakeControl
After=network.target
[Service]
Type=oneshot
ExecStart=/bin/bash -c "echo XHC >> /proc/acpi/wakeup"
ExecStart=/bin/bash -c "echo EHC1 >> /proc/acpi/wakeup"
[Install]
WantedBy=multi-user.target
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I enabled this service and started it:
/proc/acpi/wakeup now had this:
Happily this state remained after a reboot.