Error 1 Action Button doesnt work
Error 2 pickable items cant pickup but if u clicked him names gone.
Error 3 and most imp. Inventory Slots doesn’t show…
Sorry about my english 
Hello Lodeluner, to be honest there’s alot of stuff that could be responsible for this behaviour. We would need to see every blueprint this system uses to determine the source of this problem. I believe you followed a tutorial on YouTube, best thing to do is ask the creator of the tutorial to help you with this.
Also, I wouldn’t try creating complex systems like an inventory when you don’t know much about the basics of Unreal Engine. I speak from personal experience, you’re better off teaching yourself how UMG works, displaying data in your widgets and then eventually when you’ve mastered all of it begin working on complex systems like this inventory.
Goodluck with your UE endeavours!