One can clearly see an island labelled as "Ullung" (Ulleungdo) in the Sea of Japan, but there are no Liancourt Rocks. It is natural because Korea's eastern limit was believed to be Ulleungdo and it was believed that Liancourt Rocks were out of Korean territory in those days.
But please think of the Korean claim demanding Tsushima, Dokdo (Liancourt Rocks) and Parangdo - it was made in July 1951 - just around the time this map was made.
Obviously Korea's claim was received by the world as outrageous. So USA reproved Rhee Syngman, the then president of South Korea, for his unlawfullness but he didn't listen to the advice.
Adedendum: Broughton Bay was labelled as "East Korea Bay".