I tried a few times the x86_64 launcher and I didn't have this problem (I'm on Ubuntu 18.04.1 LTS).
I also tried the x86 launcher and this time I had a black screen problem (I should stop uploading x86 launcher on Linux, it never worked).
What Linux distribution are you using ? And are you sure you didn't launch the x86 launcher by accident (it happened to me) ?