We are supposed not to recommend the intallation of third party ppas, however this makes the configuration of suspend/resume so much more easy (actually, just a tick in a box) that I thought it would be worthy to post.
Install netext73, which is a software from a Romanian group who sells custom kernels for linux. You don't have to buy their kernels in order to use the fix for hibernation. In reality, you could as well uninstall it after the whole process and you would be fine.
For its installation:
sudo apt-add-repository ppa:netext/netext73
sudo apt-get update
sudo apt-get install netext73
And launch netext73:
Go through the first installation.
Check Hibernate in the optimizer.