Ooops, I misread the question.
Mark/Martin have to add some extra logic to the python code turn off the chapter numbers in headers.
Until they’ve had time to fix the python code, then can use bookhooks, (in ptxprint-mods.tex): These are untested but ought to work:
\setbookhook{start}{OBA}{\global\OmitChapterNumberRHtrue}
\setbookhook{end}{OBA}{\global\OmitChapterNumberRHfalse}
If that works, then you can duplicate it for other 1-chapter book IDs in your publication, of course.
