E.l.f. Beauty hosted an influencer activation at Coachella. VALERIE MACON / AFP via Getty Images

Influencer marketing has ballooned into a $12 billion industry in the US. And yet, running campaigns can still feel unpredictable.

Business Insider asked more than a dozen executives at top brands like Poppi, E.l.f. Beauty, and the National Football League what challenges they face when working with creators. Three common pain points emerged.

First, it's tough to find relevant talent amid a growing pool of content creators. It can also be tricky to agree on content copy when balancing a brand's messaging goals with the creator's own voice. Lastly, campaign performance can be erratic as social-media algorithms become more personalized and harder to crack.

Buying influencer ads, unlike TV spots or display ads, requires a human touch. It's tough to automate ( despite some attempts to do so).…