I've recently been playing through the story mode/campaign of this game, and has finished all levels and extra challenges... Except one.

On the tenth level of the jungle area, "Tycoonasaurus Rex", the Master Challenge is to achieve fame rank 6. I've never had an influencer spawn to do this - what must I do to get that challenge? I haven't found any info on it elsewhere. It just kinda sucks as I've done every other challenge, I kinda wanna complete the set