It does not support the Zen3 APUs out of the box. You need one of the previous CPUs to upgrade the bios. They are not officially supported, only through a beta bios. Many Deskmini A300 struggle to run the Zen3 APUs with the RAM at anything above 2400MHz.
I dont believe that there are widespread RAM issues. I have had zero issues with my A300/4650g BIOS 3.60s system running OC'd RAM @3400c16 since I built it in August. You will always see all the issues in forums but they are the minority because the people that are happy generally dont say anything.