Not sure if this will help, but this build, using the M variant of your board, got sleep working: https://forum.amd-osx.com/index.php?threads/ryzen-5-3600-gigabyte-b450m-s2h-sapphire-rx-580-8-gb-catalina-10-15-5-19f96-opencore-0-5-8-triple-boot.300/
Here's a comparison of the two mobos...