UPD This not a bug, but a feature. You can only equip one accessory with black heart
Basically, I have two rings that always occupy the same slot and switch places when equipped. It doesn’t make any difference whether I equip a third ring or unequip them all. I’ve tried all the possible combinations and even restarted or logged out.
I’ve recorded the video for a short demo Diablo 4 bug - impossible to equip two rings on PS5 - YouTube