@BillFlowerpot Do you have NRaas Traveler installed? That fixes some issues with adventures and traveling, although not everything. There's no reason to repeat the entire adventure chain either, just the last step that worked to trigger the one that's not working.
There are two other options you can use here if you don't mind cheating. One is to make another door, or edit the existing door so your sim can open it. Then go grab the treasure and don't worry about not completing the tasks. Since your sim has to be at level 3 visa to even start this adventure chain, you're only losing some money and ancient coins, both of which are plentiful.
The other option is to use NRaas DebugEnabler to manually assign the next step in the quest, to bypass this one that isn't working. The problem is that this approach often erases the data about the other adventures your household has completed in that world. It's as if DE erases all adventure-related data for a given world, then assigns the appropriate visa level and the particular adventure.
Point is, both have their drawbacks, but either one would get you some of what you wanted.
Finally, I don't know whether this would help, but you could cancel the quest and reassign the most recent step, or rather the one before, with NRaas MasterController (MC > Basic > Opportunity: By Category > Adventure > [name]). A just-cancelled adventure typically doesn't appear as an option right away, so it would be best to use MC to assign a different quest, then cancel that and look for the original one again. This doesn't erase previous progress (except for the fact that you completed the task you're assigning), unlike DebugEnabler. But you might run into the original problem yet again.