How to create multiboot USB with Linux -

I was able to get the grub menu to show up as in the given tutorial, but upon selecting an option, I just get a black screen. This occurs on both my fedora and ubuntu ISO’s. I’ve tried additional kernel arguments but they haven’t seemed to resolve this issue. I’ve also tried the flash drives on two machines with the same result, so I think it is certainly the grub.cfg. Any ideas; I’ve tried both the cfg given in this tutorial as well as the one specified in the Ubuntu documentation, all to the same result?