Limit on objects in the library?

I’m not sure whether this is right but is there a limit to how many objects can be in the library? Because for some reason once I add the last two objects into my project a white box appears on the stage, but it disappears when I delete those two objects out of the library (or any other two for that matter) is there a way to overcome this? I’ve sorted all my objects into folders and that’s not working either…