I have a campaign with a $50 budget set. I have 5 ad sets, each with a difference audience variable. I then have different 4 creatives in each ad set. So in total have the same 4 ads appearing 5 times.
My questions is, why is creative 4 getting so little traffic? yet it has the best CTR. I Feel like it's impossible to judge how well this creative(4) is doing because it's been allocated such a tiny percentage of traffic and share of the budget. Why does FB do this?
Facebook automatically allocates spend to the ads which it thinks will best deliver on the ultimate objective you've set for the campaign, which isn't necessarily CTR.
If you really want to force spend to an ad, pause the other low performers in the ad set. However it's common that you might find that CTR goes down with more impressions - or even that the ad still refuses to take spend as Facebook's algorithms can't find audiences for that creative on your objective.
In general make sure your objectives are set correctly and then lean into ads that are scaling spend AND getting you an acceptable outcome for the ultimate objective you really care about. This won't necessarily be the ads with the best CTR.