Set the multi-function cooker to high sear and heat the olive oil until shimmering. Pat the shanks dry with paper towels, and sprinkle generously with salt and pepper. Sear the shanks in the cooker until deep golden brown on one side, about 5 minutes. Turn and sear the other side, about 5 minutes. Reduce the heat to medium, remove, and set aside the shanks. Whisk the broth, wine, and tomato paste and add to the multi-function cooker. Bring the broth mixture to a simmer, scraping the bottom to loosen any browned bits. Turn the cooker to manual low and add the carrots, onion, garlic, thyme, bay leaf, and allspice. Nestle the shanks on top of the vegetables, cover, and cook until fall-apart tender, about 4 hours.