What is the item you are trying to add in?
Are you cooking it and testing in game?
Have you tried giveitem in the editor in the test map level?
If you have it put in correctly in the master item list, and you use the array index on the left to add it in then even if you haven’t put in the structure details or other parts it will spawn the item.
Another reason it won’t spawn your item is if you aren’t loading your custom mod data, and just loading the generic TheIsland data instead, best way to test, is open the TestMap level in the Maps folder that came with the game and set the Primal Game Data Override to your custom PrimalGameData_BP