I made the distinction because post 4 reported success with one of those boards. Searching the X570D4U thread, I see similar comments of ECC error reporting working. Whatever issues ASRock may or may not have, it doesn’t seem to generalize to a particular chipset — but the Rack boards have BMCs with another reporting path.
Searching more broadly, I see one report of ECC errors working on the X570 Taichi, although it would have been a few BIOS versions ago by now: