Hi this is my version of a tool for relinking (missing) bitmaps which can not be found for whatever reasons (changed paths, moved files etc.). It is pretty straightforward and works with almost any type of asset (maps, HDRIs, IES files) as long as it can be referenced and seen in the asset browser. Due to copyright restrictions I can not publish the code right now but I hope that it can help you anyways until max itself has a better management for assets.
Instructions