Inconsistency on the sales endpoint

I've noticed on your frontend that when I click on a listing, and try checking it's sales history, for item with id A it shows up 5 items sold, and for the same item with id B (so basically the same item with same wear etc but another listing) it shows up more or less than 5 listings. Now I went on and checked out these API endpoints:

https://csgoempire.com/api/v2/trading/item/304457816/sales

https://csgoempire.com/api/v2/trading/item/314227673/sales

and the responses differ. It is the same item: ★ Moto Gloves | Smoke Out (Field-Tested)

however the sales history is inconsistent. Is this an API bug or something ? since it's also happening on the UI. I've noticed this just recently.

Also I checked with another post where I've got this endpoint:
https://csgoempire.com/api/v2/trading/item/market/sales?name=%E2%98%85%20Driver%20Gloves%20%7C%20Imperial%20Plaid%20%28Field-Tested%29

and even here the sales history for a skin doesn't include all the sales.