try
tbminer --list-devices
what do you get?
Available Cuda devices
-----------------------
Available OpenCL devices
-------------------------
Device Number: 0
Device name: Ellesmere
PCIe bus id: 1
Memory: 3GB
Device Number: 1
Device name: Ellesmere
PCIe bus id: 2
Memory: 3GB
Device Number: 2
Device name: Ellesmere
PCIe bus id: 3
Memory: 3GB
Device Number: 3
Device name: Ellesmere
PCIe bus id: 4
Memory: 3GB
Device Number: 4
Device name: Ellesmere
PCIe bus id: 8
Memory: 3GB
Device Number: 5
Device name: Ellesmere
PCIe bus id: 11
Memory: 3GB
Device Number: 6
Device name: Ellesmere
PCIe bus id: 12
Memory: 3GB
Device Number: 7
Device name: Ellesmere
PCIe bus id: 13
Memory: 3GB
Device Number: 8
Device name: Ellesmere
PCIe bus id: 14
Memory: 3GB
This is a driver failure. Clean your system with DDU and reinstall the driver. Use old driver - 1.9.7.4 for example runs fine for me with the old RX580. New driver bring no benefits for the RX580