What is the expected behaviour of the Unity Cookie dialog? (iOS)

I enable ads with Advertisement.Initialize(XXXX,false) (i.e. not test mode), test mode is set to OFF in services, and "Override test mode" is ON ("Force test mode OFF") in Unity Dashboard.

I'm still seeing the 'Can the Unity cookie collect and use...' dialog box at the start of every session, and sometimes multiple times per session. Weirdly it's always a 'State of Survival' advert too!

So what is the expected behaviour? Should the user only see the 'Unity Cookie' dialog the first time an ad is shown? Or is this behaviour normal?

Assuming it's not normal, have I maybe missed something? Should I turn 'override test mode' off? That's about the only thing I can think of...

Thanks in advance!