Hello, just a hint for those who are having ext4 partitions mounted: that will prohibit suspend to work.
Pardon for my unscientific claim, but If I'm not correctly mistaken this was related to changes that made syncing disks faster in halting. For a long time I thought that also was affecting ext2 partitions too but a few weeks ago I was happy to find out that it only affects ext4 partitions, even in readonly mode. Wanted to share my findings since there might be someone else pondering why the suspend doesn't work. Unmount the ext4 for good and be happy. -- Kind regards, Ville