I did check it again yesterday and today using 'systemctl suspend'. The bug does not always happen, e.g. yesterday I was able to suspend my system 4 or 5 times in a row properly, but tomorrow after the first attempt the PC woke up again by itself ~2 seconds after I suspended it. So yes, the bug is still there unfortunately. I have used 'pm-suspend' almost exclusively during the last two months and this bug never ever has happened with 'pm-suspend' during that time (or in earlier Ubuntu releases).
I did check it again yesterday and today using 'systemctl suspend'. The bug does not always happen, e.g. yesterday I was able to suspend my system 4 or 5 times in a row properly, but tomorrow after the first attempt the PC woke up again by itself ~2 seconds after I suspended it. So yes, the bug is still there unfortunately. I have used 'pm-suspend' almost exclusively during the last two months and this bug never ever has happened with 'pm-suspend' during that time (or in earlier Ubuntu releases).