[NTG-context] Doublesided option is clearing head & footer (MKIV)

Hello all, When I set: \setuppagenumbering[state=start,location=footer] then document is generating OK, with defining header and footer. But when I set: \setuppagenumbering[state=start,location=footer, alternative=doublesided], then header and footer of page is drop out - no pagenumger, no hairlines etc! Where is a problem? Thanx Jaroslav