In that case, it seems like those white characters are using different markings then the ones you have downloaded, as you suspected.
As in, if you're using the aug 22 ones, you will see characters with the legendary markings as different or white, even though you have a marking pack downloaded.
Are they your characters or other peoples'? If they're white for characters you are using, have you tried clicking on any different marking?
If it's other peoples' characters that show up white, I don't mean to sound repetitive, I'd download the Legendary markings, as Acca provided. They include the some from the Aug 22 pack.
And make sure you're following Acca's instructions exactly. If you don't, characters will still show up white.