To fix the insanity aspect (repeating same steps and expecting different outcome), this morning I did a test build on a different system and it worked fine. My resulting ISO booted with no errors.

So, there is something different about the original build system which is functioning fine otherwise.

I will continue with my customized, remastered Knoppix disk on the different system now. It may be helpful to troubleshoot the issue should I find the time but for now I will continue my work and be done.

Thanks for all your attempts to assist.

Regards,

Job