If you want to get technical, AFAIK, the 5xx-series AM4 chipsets are not "officially" compatible with anything pre-Zen2, which includes the 3200G/3400G ("Zen+") APUs.
The A520 chipset was specifically produced for the 4000-series Zen2 ("Renior") APUs, which AMD then decided to NOT release for DIY / retail market. So A520 mobo vendors were kind of left out in the cold. That's why they are so cheap. They do work with Zen2 / Ryzen 3000-series CPUs, with a discrete card, but since they don't allow overclocking, and are low-end, they aren't popular for that task.