Instanced Static Mesh Component Instances in Distance Index Changes

Good afternoon, I’m using UE4 4.22 on Mac OS Mojave. For some reason both ISM and HISM instances that are a certain distance from the player character cannot be removed using their initial indices. This seems really strange to me and I can’t figure out why exactly this is the case. To reproduce I have set a thousand mesh instances in a square around my player, each 1000 units away storing each of the corresponding indices in an array. I then iterate through the array and remove each index, but for some reason the indices farthest in the distance are only removed after I get closer to them. Is this expected behavior? Is there any way around this?