I was editing a polygon shapefile in QGIS (3.0.1) today when suddenly 966 out of 5382 polygons disappeared from the map. I had been changing attribute information in the table, cutting polygons, etc as I was going along and saving my shapefile regularly. The polygons are still in the attribute table (if I select all my polygons using a spatial selection and then inverse the selection, the lines with the missing polygons show up) but an error message (zoom failed, feature has no geometry, "le zoom vers l'entité a échouché, l'entité n'a pas de géométrie") appears when I attempt to find those polygons. There was no spatial clumping to the lost polygons nor a common attribute.
Comparison of yesterday's file (purple underlay) with today's corrupted file (black hatched)
I can't share the file because it is proprietary so I realize that it is limited what can be troubleshooted just on my description. I have the back-up in our server from end of last workday so I will have only lost one day of work but it is still frustrating.