There is an issue with APUs and bios modded GPUs, they can't go along on win 10 build 1803. There is a driver issue caused by win 10 (error 43). You must keep your original bios to use the Vega cores from Ryzen G series.
This error 43 occurring in case of a modded bios has nothing to do with JCE Miner.
The culprit is the AMD graphic driver which rejects every modded bios.
The workaround is simple: The tiny application atikmdag-patcher patches the driver to make it to accept any bios, bypassing its signature inspection.
This patch is required after each install or update of the graphic drivers, if at least one GPU has a modded bios.