iOS Certificate Fails to Load with Provided Key

HI, I can’t get the iOS configuration to be accepted by Unreal.

I’ve created a Provision file and imported that in the iOS project settings, but when I try and import my iOS certificate and validate that with a key when prompted, I get this failure error:

I only have one p12 key to go with my .cer certificate file, so I can’t understand why the validation is not being authorized.

I’ve tried deleting the certification and creating a new one, no luck though. Absolutely stuck, any help so appreciated