Something similar has happened to me with place names, where it has changed to another place in my file, but if you look at all the people or events associated with that place these "changed" records do no show as linked to that place.
In my case it was 6 records attached to Boone County Indiana that had gotten overwritten with a town in Massachusetts (where I had over 100 people attached).
I went in and manually changed the places back one at a time. (I actually copied the file over before I did this, and did this in the copied file as a test). I changed the first one, but made sure I was only changing a single instance and not the "all instances". Then, I went to change the next one. I noticed that the number for the "change all" had decreased by one, and that it was only reporting the number based on the number that would be correct for Boone and not the Mass. town.
I had something similar happen before a few months before that. It is like the data value for the place gets overwritten with text for another place but not actually "changed" at a deep enough level to be linked with the place that had that actual value.
Tech support is clueless on this.