The GenTokens option begin on weekstart is ignored when GenTokens token is inside a mini-calendar (ie. placed in the same box, and after, a mini-calendar token).
If you want a GenTokens inside a mini-calendar to start on the start of the week that contains the 1st of the month, then use the :ws embedded tokens weekstart mini-calendar modifier instead.
Topic 178160, last updated on 19-Apr-2020