I imagine you beer folk out there have a lot more experience purchasing beer via Internet-and-pick-up means than I have. Twice this weekend I ordered beer late in the evening via various MA liquor store websites, made the fairly long trip in the morning to pick up the beer, and be told when I got there the beer is not available. I'm now in "Second time shame on me" mode. Are there MA stores notorious for not having accurate on-line inventories? Are most of 'em like this? Are any safe to use online knowing when I get there what I purchased is what I get? It's very discouraging, and I don't want to be making unnecessary trips during COVID times (though according to the state of MA, beer/wine/liquor IS absolutely essential!) Breweries, in my experience, are fastidious about maintaining their online inventories. But they're selling only what they're making now. That's fine and very appreciated, but occasionally we want to buy something that isn't recent and a packie is the only way to go.
Sorry that has happened to you. Maybe call beforehand to ensure your order is taken care of? My guess would be that there would be lag between the actual inventory and online inventory and the online inventory might not be updated (possibly manually) until the morning. Late in the evening seems like a not the best time to place an order. Remember that for many of these stores, the technology is new, and they're doing the best they can.
I'd think that late in the evening is the worst time to order online - most places will update inventory overnight. SO something that sells out during the day doesn't necessarily show accurately online. But I agree that best bet would be to put in a phone call to make sure it's taken care of before you leave. One would think they'd communicate on attempting to pull orders, though.