updated icons not updating on old posts only new

when i change the icons, it seems the images break on the old posts when i say yes to trying to update them with the new changes. it asks if i want to update the old posts so i assumed thats what it is trying to do, but it just breaks. any fix for that? cause now i will have to get Duplicate Posts to redo each post if i want to change the icons. im just starting my site build now but in the future that could turn into a lot of work.