I went to the woodworking table as a level 10 in handiness skill and there is no option for the wooden throne. So I made the toilet hoping that would complete the mission, I know it’s not the same but I tried it. Of course it didn’t work.
Also, I went to the cave and in my game it’s already broken into, so I explored it and it didn’t check off the mission from the list.
Edit: my game is updated to the latest version and I have no mods.
I had the same problem. You have to claim the wooden throne from the event first and then you can make it on the woodworking table.
You need to choose the option to “travel to Forgotten Grotto” after you have explored it. Then the task should be checked off.
I saved and quit and went back into the game and it worked.
I have this same issue. I did everything except the final task, which is to build the wooden throne. Level 10 handiness, but the throne does not show up in the pie menu. Still hoping to find the solution to that issue.
On the other hand, I was confused about the cave, too, since I'd already broken into it. But then a message popped up to "share" thoughts or experience (can't remember) about the cave with two Sims. Did that and it worked.
Hopefully I can figure out the throne issue, since that's all that's left for me.
EDIT TO ADD: I found the solution. Claim all available "rewards," the last one being the wooden throne. Once you do that, the wooden throne is available in the pie menu for the workbench. YAY!
Did you claim the reward object Throne, by chance? This was a stopper for me on Week 2. I failed to claim an item, because I didn't really want it. Turns out, that's really not an option. So, I went back and claimed it then for good measure, I clicked Claim All. Did the trick for me.
