Create ISO but not bootable

[Jeremy-A-H]

My iso for 6.7 gets created in the /home/%user%/kubam folder but when I mount it to the iso either via vmedia or just through a standard KVM connection it's not bootable. Am I supposed to do something special to make that iso bootable. If I mount it in the OS it looks the same as the normal esx 6.7 iso other than I see the new KS.CFG file I expected to see.

I also have the same issue with esx 7