I want to buy a chicken but I go to the store at 9AM and Marnie immediately leaves without opening shop. I followed her (creepy, huh?) and she goes to the store where she exercises with a bunch of women until 7PM and then goes home to her closed shop. How am I gonna get a chicken under the circumstances? Other shops close for the day when they're not available but Marnie leaves it open but just isn't there all day. Are there "exercise days" and "shop days" that are unmentioned anywhere?
Had the same with Willy. Found him fishing by the river, store was open just unnatended. Visited Pierres(?) at 4 or 5 and he was tending to shelves meaning i couldn't purchase anything even if i spoke directly to him.
Everybody keeps to their own schedules and as you get to know them you get the hang of their schedules. Go in the next day and she should be there.
If you want to know about a character's schedule, all the schedules are listed on the wiki per character.
From what I can remember, Tuesdays have the fitness thing so Robin and Marnie are both MIA from their shops. Also I think every villager has a doctor appointment (either a Tuesday or a Thursday) in the year that takes them from their respective business but I've never taken the time to really check/verify those and which days. And if you fix the community center, it causes Clint to leave the smith on Fridays.
Pain in the butt, especially since he kept such regular hours before. Luckily, I had my watering can fully upgraded before then. Oh well, at least he's not hanging around his shop all year round?