Year range The Herculoids

Currently, The Herculoids has a year range of 1967-1969: https://www.imdb.com/title/tt0061262/reference/

However, as you can see, all the episode are from 1967-1968. 

TMDB also has the year range as 1967-1968: https://www.themoviedb.org/tv/3578-the-herculoids/season/1/episode/36 

The same goes for epguides.com: https://epguides.com/Herculoids/ 

Can a staffer look into this and correct this please?