Birds not eating RSPB Feeder Mix

I have just changed from RSPB Favourites Blend Extra to Feeder Mix. The sunflower seeds in the Feeder Mix are husked. The feed is in a RSPB Classic Peanut feeder.

This summer the feeders have been taken over by larger birds,  such as Starlings,  Great Spotted Woodpeckers,  and Magpies.  They gobble up soaked mealworms and like the RSPB jumbo suet blocks. Unfortunately the Feeder Mix isn't being eaten.  

Can someone please advise. I have a 12kg sack of Feeder Mix...