Questions, problems, or anything that looks wrong — louis.genestier@protonmail.com. A real person reads it.
Most often, notification permission is off. SaleAlert checks prices on its own servers and has no other way to reach you — open iOS Settings → SaleAlert → Notifications and turn them on.
Otherwise: the app may not have dropped below its usual price. A price that falls from 9,99 € to 8,99 € when it normally costs 8,99 € isn't a sale, and you won't be told about it.
Every watched app is re-priced at least every few hours, whether or not the app is open on your phone. A very short sale can still slip between checks.
Two ways. You can tell it when you add an app — useful when the app is already discounted that day, which would otherwise make the sale price look normal. And it works the price out itself after a few weeks of watching, by taking the highest price the app has actually held for a meaningful stretch.
When both are known, the higher of the two is used, so an underestimate can't hide a genuine drop. You can change your figure any time from the app's page.
A free app has no price to drop. Search only shows paid apps for that reason.
Prices differ by country. Check that the storefront in Settings matches the App Store you actually buy from. Changing it clears the stored regular prices, because prices aren't comparable across countries.
You don't — skip it and SaleAlert works it out. Until it has, you'll be told about drops from the last price it saw, which is a weaker signal.
Settings → Delete my data erases your watchlist, your installation identifier and your push token from the server immediately. There's no account, so that's everything held about you. Deleting the app also stops all processing.
Email louis.genestier@protonmail.com with the app name and what you expected. Wrong prices are worth reporting — they usually mean a storefront mismatch, and that's fixable.