I have been having this problem for a while where the computer upon clicking suspend (or even typing systemctl suspend in the terminal) the display goes black for 1-2 seconds and turns back up in the lock screen.
I have tried the following command:
cat /proc/acpi/wakeup
Which shows this:
Device S-state Status Sysfs node
GPP0 S4 *enabled pci:0000:00:01.1
GPP1 S4 *disabled
GPP3 S4 *disabled
GPP4 S4 *disabled
GPP5 S4 *disabled
GPP6 S4 *disabled
GPP7 S4 *disabled
X161 S4 *disabled pci:0000:07:00.0
X162 S4 *disabled
GPPA S4 *disabled
GPPB S4 *disabled
GPPC S4 *disabled
GPPD S4 *disabled
GPPE S4 *disabled
GPPF S4 *disabled
GP10 S4 *disabled
GP11 S4 *disabled
GP12 S4 *enabled pci:0000:00:07.1
GP13 S4 *enabled pci:0000:00:08.1
XHC0 S4 *enabled pci:0000:09:00.3
GP30 S4 *disabled
GP31 S4 *disabled
PS2K S3 *disabled
PS2M S3 *disabled
UAR1 S4 *disabled pnp:00:01
*disabled serial-base:00:01:0
*disabled serial-base:00:01:0.0
GPP2 S4 *enabled pci:0000:00:01.3
PTX2 S4 *disabled pci:0000:04:00.0
RLAN S4 *disabled pci:0000:05:00.0
PTX1 S4 *disabled
PTXH S4 *enabled pci:0000:02:00.0
I have the tried to disable all of the enabled devices with this command(obviously typing the actual device in the place of [DEVICE])
sudo /bin/sh -c '/bin/echo [DEVICE] > /proc/acpi/wakeup'
...but even still nothing worked.