So I just found out that I didn't quite build the loot drop system correctly, and it only worked for developers. However, I believe (and hope) that I’ve managed to fix the issue. It’s my first time using the Steamworks API for the inventory system, so I’m still making a lot of mistakes, but I know that’s not an excuse. I’ll make sure to fix everything as time goes on.
I'm still closely monitoring the loot system, so there will be more updates about it.
Thank you, and have a great day!