Strange Parralax Background issue (misplaced on load)

Thanks for the reply. The URL is:
http://clients.tino-designs.com/dr-russ/

I also posted it in this thread (those users seem to have the exact same issue but the solution in that thread is not helping me much): https://colorlibsupport.com/t/line-over-the-main-picture-in-parallax/

Againg thanks for the help.