Yep, I would not recommend Ubuntu if you would like to use hibernation. Not sure why Canonical though it good to screw this up so much, but this is the case. I used to be a Ubuntu only user, and this was the main thing that pushed me away.
I use Arch btw.
Agree, it is a pity, but not a lost cause! There have been so many hit-and-miss, u-turns and improvements in Ubuntu, and some other distros, that it should come back soon 
I found some users here, left in the dark: no reply, comments closed
I am pretty sure it has more to do with tweaks and small customisations that I’ve done on my system. Sometimes I can’t help it, that is the beauty and the freedom of Linux and Open Source!!
If I had more time, sorry, WHEN I have more time, I will test on another partition and a fresh install. Also I intend to install a fresh 26.04 in a few months (once stable) as my main system. I could fiddle around with other distros, like elementary or Pop! Os, but I need my every day working machine in priority.
So I am willing to test and fix things, to keep the Hibernate feature working and reliable. And document it as bast as my abilities. @Matt_Hartley What method/process would you recommend, please?