Phoenix Miner 4.2c have full support AMD drivers up to 19.4.3. On later drivers miner woudn't use optimized and double kernels and may (and will) cause many rejected shares.
We need miner update to use new drivers...
why would you want anything above 18.6.1 for polaris?
wouldn't it be nice to have an option for devfee in ZIL? along with coin switching for the time there's no POW on ZIL...

For full support AMD cards on Windows 10 x64 1903 drivers must be at least 19.5.2.