After seeing Peter's message [1] I tried suspend/resume on XFCE but I
still got same result. I could hear hdd spinning up and cpu fan
working, but power led would still be in suspend mode - just blinking,
with screen off.
But with LXDE suspend/resume works flawlessly! In LXDE suspend works
as expected with "pm-suspend" command and resume also works with power
button. I captured full kernel log of suspend/resume [2], it is
obvious not an kernel issue...
Does anybody have a clue what to troubleshoot further?
[1]
https://bugzilla.redhat.com/show_bug.cgi?id=1162793#c1
[2]
https://bugzilla.redhat.com/attachment.cgi?id=958090