We have many records that already existed in our database with a * in their last name, but otherwise blank. A few constituents made a donation, but their names were not updated in the system to overwrite the * character.
In order for a constituent's name to be updated by a donation, the first and last name must be completely blank. Since there is a * character in the last name, the system interprets that their name is not blank and thus will not be overwritten. There is a site setting that will insure that the name and physical address entered on the donation form will always update their constituent record based on whether they are logged in or not. For more information, see Donation form is not updating constituent's address.