Lost mission! (Red Dead Redemption 2)

Faced with this problem again for up to 4 heads just arrived in a new city of Saint Denis, which Is the biggest on the map it was 3 new jobs! Started is s a mission where you gotta get to save his son John, after its completion, I discovered that the remaining 2 missions was gone and there were others in the city, so with these two missions, why they disappeared