Ark Dev kit dont start

Hello, install the ark dev kit with epic games launcher. All is fine. I start the dev kit … it runs and runs … after 1 hour the cpu tells me 48% for the dev kit. at the task bar is an icon for the dev kit thats all. I use win 10 on my notebook with gtx980m.
Than i install UE4.21 for testing this works only i extend -dx12 attatched at the exe file. For the dev kit i can not enter this parameter.
Anybody an idea? I have done dxdiag verify an so on nothing helps.