[NTG-context] Bug in footnote mechanism when compiling per chapter?

I had in my project file \definenote[endnote][location=none] \setupfootnotes[conversion=set 2,way=bypage] which I moved to my environment file. But wherever I have it, when I compile per chapter, the footnote mechanism fails because it runs out of symbols to use. When I compile the entire book. no such problem occurs. Is this a ConTeXt bug? G