Ubuntu studio 20.10 sleep mode stopped working
I had a very similar issue after the update that was applied to my system today (Ubuntu 20.04 / Lenovo Legion Y540). When closing the lid, it looks like the laptop only goes partially into suspend mode. The screen goes off, the wifi goes off and maybe some other things as well, but the keyboard stays illuminated and the fan keeps running.
I tried different suggestions which I found on the net like:
Suspend on lid close not working
and
20-04-lts-since-upgrade-from-19-10-laptop-doesnt-suspend-anymore-after-lid-clos
but nothing helped.
Then because of this thread nvidia-460 ,
I changed the nvidia driver from 460 (proprietary, tested) to 465 (proprietary), rebooted and the suspend mode worked again. I changed the driver via 'Software & Updates' => 'Additional Drivers'.
Maybe worth to try ...