[NTG-context] bug with \setuplist[part][after={\blank[samepage, big]}]

Dear list, I don’t have a minimal sample (yet), but I have added the command above to force part titles in contents to be with the next part title. Well, the contents take five pages and two of them finish with a part title. Am I missing something or is this a bug? And if it were a bug, would it be related to wrong page breaks with titles? Many thanks for your help, Pablo -- http://www.ousia.tk