Active Campaign Add-On - Keys not updating for Custom Value Mapping

Trying to map some custom form fields (Values) to the Active Campaign Keys but the Keys are not updating;

In another website we manage, the Key field shows a dropdown where you can select the Active Campaign field that you want to map to the form Value.

I’ve tried refreshing the API token, deleting the AC integration and starting again… but for some reason it’s not updating the Key fields to select so we can map to the form fields.