When I updated 2 of my HTPCs (1x Gigabyte Brix and 1x Intel NUC) to 12.0 I noticed intermittent issues with suspending Kodi that never happened before on any previous release I'd used.
If I suspend the machines now, sometimes they work as expected but frequently they get stuck, the display goes off but the power lights remain solid (as opposed to blinking) and the machine is still running. If you resume the machine again, Kodi comes back but there's no network connectivity so you have to reboot. This is very frustrating and has led to me accidentally leaving the machines running for days at a time when not in use.
At first I assumed it may be a compatibility issue with my settings/addons and after much testing without any change (even updating the most recent nightlies for 12 and 13) I decided to install a clean copy of 12.0 with no changes. This resulted in the same behaviour (log below).