[NTG-context] 4UP with no table of content - bug?

I have this 310-page book with a table of content that is alsways fine when I use a single page layout. When I switch to \setuparranging [2UP,rotated,doublesided] it also prints the table of content, however, if I rerun the job for a second time using the 2UP, the table of content disappears. Is it a bug or do I need to do something special? thank you Ciro