This may not be the fix you are looking for, but entering “r.Streaming.PoolSize = 1500” into the console should fix the issue. I think the default is 1000. I believe the message has to do with how UE4 caches textures when opening a project or displaying a scene. There are other settings/console variables dealing with texture streaming. What I did was just add the command into the engine’s consolevariables.ini so that it just always defaults to the above. I also have noticed that it will scale the value on its own sometimes depending on the amount of vram on the gpu.