Some icons may not be shown since it not all completed. Bulb, icon artist for this game, is still working on creating more icons in future updates. If you reading some update logs, there will say that which icons that Bulb created in those updates.
Oh, I think it isn't normal at all. Have you try to re-download and replace a new one to an older one?
Anyway, I use Windows 64 bit but I think it doesn't related to this problem. Also public build already have icon pictures for some items so it should have some items which display with icons and question mark icons for some items that don't have it own icons.