WIM to ISO fails, failure when attempting to copy boot files

Question

I am facing a bit of a conundrum.

I've been trying to form an ISO from a WIM for some time now, but always run into the same error:

It plays up nicely, merges the swm-files as well, but in the end the error comes:

failure when attempting to copy boot files

It may be that I miss the forest for the trees, but I can't find the error.

I am already in the subfolder where etfsboot.com is.

oscdimg -n -m -o -betfsboot.com C:\ZZ C:\YY\XXXXTestimage.iso

So my command, which was also executed. On C:\ZZ are the subfolders like on a deployment stick, in the subfolder "target" are the swm-files, the files were adjusted so that it assembles the swm-files (it did this without any problems).

But why can't it write boot files?

Where exactly is my error in thinking that I don't see?

Would be cool if someone here looks into this and maybe sees the needle in the haystack.

Thanks in advance.

applying the iso in the vm

oscdimg without any problems

I just try to create an ISO from a WIM-file

I also splitted the WIM-file and put it into the target-folder