I'm using the Radeon Blockchain Compute Driver Version 17.30.1029 for every card.
Well, this is exactly what I was suspecting. I was fairly clear about GGS supporting only Adrenalin 17.12.2 and 18.1.1.
There is not much I can do when you run GGS with a deprecated, unsupported driver.
Maybe I should add a warning about unsupported drivers...