I'am reverted back all rigs to 18.3.4, because, the newest drivers has a bug - some cards are detected as RX580, but they actually are RX570. And in my IMHO, 18.3.4 is more stable.
Yes, in 18.6.1 my Sapphire Nitro+ RX570 4GB is detected as RX580.
But is that a problem?