Missing surfaces come up frequently, since they are most obvious when looking at the model. But any missing attributes can cause problems. Missing fills can cause issues with library parts not reading properly, and can cause files to slow down.
Fills are also a sub-attribute to surfaces for elevations, sections, and interior elevations. This can be a problem, since the missing fill can often be represented by an undesired fill surface fill in the elevation view. In example below, the fill that went missing was a surface fill for a tub filler. It was supposed to be a simple screened fill, but had been replaced with a really complicated detail fill, as the default “next closest fill number”.