When using the General Search, a record is not returned if the search string is contained in the Last Change field as well as in the Name field.
For example :
I log on as rgdobie
When using Advanced search to search exactly for a surname of Dobie, I get 99 matches
Sorting by the Last Change field shows me that 38 of these have a value and 61 have no value.
When using the general search (with 'Exclude some non-genealogical data' set on) and searching for Dobie I get 61 matches - those records with no value in the Last Change field.
I believe the missing records are excluded because of the dobie found in the Last Change. They should only be excluded if that is the only match. If a legitimate match is found, in say the Name field, these records should be returned.