I don't have an issue, but just a general question. The way I've done this up until now is by just inserting a number value but not putting it into leaderstats. For example, a backpack in a simulator for how much it can hold do I just insert a number value? I just want to know if there is a better way to do this. Thanks.
Create a folder in the player, call it Stats. This will be the folder for the things they have, backpack capacity, how much currently in their backpack, etc.
Also, don't use NumberValues for backpacks. Instead, use IntValues. NumberValues have floating point errors, and extra precision you don't need!