grind on 7 bird poohs

after i did the objectives, my whole entire game just lagged and now every single time i open the game, im stuck in the place where the “grind off the rail” and collect all 7 bird poohs, but now the poohs aren’t even showing anymore and the challenge never ends. i’ve even tried deleting and reinstalling the game 3 times and still i’m stuck on that god forsaken challenge. i just want to progress and unlock everything so this is really annoying. it’s been 3 days and still it’s stuck. there’s no way to restart the challenge either so idk what to do. does anyone know what to do/ has this happened to anyone else?