Cookie wanted me to bury a time capsule, I buried it almost right in front of her house. It's been a couple days now and the X mark spot is gone. Is Cookie still going to ping me to dig it up? or did I do something wrong for it to disappear?
Yep, and if, by chance, the villager has moved out when it reappears, you get to open it and keep what's inside. Normally they'll send a letter, too, telling you to dig it up and keep it
Sometimes, the villager will ping to ask for it back, and sometimes you might see the dig mark before then! If you do, just dig it up and bring it to her unopened and she'll be happy
Better use the beach next time for nothing can spawn there. If you see a crack in the sand it's bound to be a capsule, meaning that villager needs it (even if you haven't talked yet that day).