I've seen this happen again and again,but cannot explain it : at any given time, one can view a feature class in ArcCatalog and not see the features because the Extents have changed radically; typically in an eGDB. How does that happen? The fix is easy, just recalculate the extents, but knowing the cause of the problem and resolving that is a better fix.
The only time I have seen an extent change is after a geometry edit that I discarded.