Just solved the problem, I decided to check the InventoryUMG project to see what might be with Lengths + Print String, it’s because the array reference was in the trigger itself, it must be instead on the Player Pawn or Controller in order to make the index to increase +1.
For those wondering how it works with names and Tags, the Variable Name called MissionName is inserted into the Array reference, and then it’s passed into the save Array, when he loads it, it will compare with Actors with Tag, so you also need to add a Tag with the same name for each instance to check correctly.