There could be a few possibilities:
* Typo: Perhaps you misremembered or mistyped the name. Double-check the spelling!
* Newcomer: It's possible that Mason Kerwick is a very new actor with limited credits, not yet widely known.
* Different medium: He might be involved in theater or other artistic areas instead of film and television.
If you can provide more information, such as the type of projects (genre, era), or any other details about the actor, I might be able to help you find him.