How long ago were the purchases made, and what setting (duration) do you have for recent purchases?
You can change the period recent purchases are displayed in my eBay, and that can range between 7-60 days (it can also be set on "current month", which means less than 7 days a the beginning), but I think 30 is the default and occasionally there's a glitch where it will default to a different setting.
You can check what yours is set to under the Purchases heading, and can change it if you need to.
You may also be able to find them in the archived section of purchase history.
If that's not the issue, try checking your emails (PayPal receipt etc) for the item numbers and then seeing if the listings are still active. If by some chance the listings were removed by eBay, (although you should have received an email about it), then the listing won't be visible on eBay at all, including in your purchase history.
