I just performed a custom constituent import, but when I view the report for my import it shows that fewer records were updated than were in the upload file. It does not say any records were skipped and none of them produced errors.
When you perform a custom constituent import, depending on the update setting you chose, some records may not require updating and thus will not show up as having been updated, added or skipped. If all of the data in your import file matches what is on the constituent record, no updates will be made. For example, if you set the update action to update blank fields with data from the import file, if all of those fields are populated on the constituent record no update will occur. If you are concerned that this is not the case, try performing the import operation again. If that does not fix the problem, contact support with an example of a constituent that should have been updated but was not.
Note: If your import did not update any records at all, please refer to this solution.