Been getting and completing them every week until this week. Option to get the 4 overland kill missions is just not there for my main. Can still get it with my alts.
Are you sure you completed all four of the previous week's? It won't re-up until you have. If so, you might want to open a support ticket...
For weekly quests like the overland ones where the reward is the same from week to week, if you finish it AFTER the time it resets, you cannot get a new one until the next reset. The T1 heroic, T2 heroic and Event Heroic weeklies work differently because the reward chances each week, so they can be 're gotten' any time between the current reset and the next reset, whenever they're finished. The solo instance weekly, overland weeklies and raid quests, that have the same reward every work, however, canNOT be picked up again if they're finished after the weekly reset. The Celestial quest works the same way, though it's reset is monthly.
This might be the same issue reported here. Hopefully it is, because a fix is incoming!!!!!!!!!!!!!!!!