Inventory slot bug?

I started fortnite last week because of a friend. Yesterday when I started fortnite and started playing the bug came up I went to the inventory and switched to the last slot but I was only on because 4 normally if you switch to the left you should get to the 5 slot but not with me (as if there were because 5 slot not with me) could you help me?

Hello if there's nothing in there you can't go.