[LLQE] Royal Enovy does not arrive at Magnolia Park/Not winning chess

As the title says, I won the chess match against the royal envoy, but the task did not validate. When going in the UI the rewards were available but nothing happened when pressing the buttons.

I saved and restarted the game, but it was way worth as I couldn't even open the UI (screenshot). I restarted the game once or twice before being able to open it again. BUT when I was about to get the reward, they already were reclaimed. I looked in my sims' inventory and in the family inventory : nothing.

Now the royal envoy does not show up in the park, I can't play against her and I can't call her to come. I started a new save : same issue. I repaired the game : same issue with both saves.

It's okay if I don't get these rewards, but I'd like to continue the quests to get the others, and I'm blocked.

All of my mods and CC are removed, and I play with the last version of the game.