Solved
Nature’s Calling event can not be completed.
The event claims I have cleared all the weekly quests, but the game won't give me the popup for "Secret Sands" to start the final chain it says I have available.
Not sure what to do now.
Sort of solved this finally. I renamed my old Sims 4 folder to "The Sims 4 (old)" and then rebooted my game. In a fresh save with a fresh sim, the popup finally appeared. Hope this helps anyone else with the same problem.
