For a product to show up in Style Arcade, it needs to have at least one of the following against them:
Stock
Sales
Purchase Order
Your date range filter could also be limiting the results, so make sure you clear your date range to all time!
FAQs:
Q: Why do some products don't show even when it has all three (stock, sales, purchase order)?
A: The way our app behaves is that, if a product hasn't had any sales, stock or PO data across ALL STORES at ALL TIMES, then it does not show.