Comic Books- The Case of the Missing Cover Girl

[Rex fury]

I just picked up a copy of Gold Key comics Scooby Doo #1. The cover advertises the "Night of the Missing  Knight", story. I've seen this art many times over the years and not thought to much about it. However, when I showed it to my daughter she immediately pointed out that Velma is missing! Anyone have any guess as to why this member of the gang is AWOL?
🤷🏼�♂️RF