Changes to Model Dont reflect in the api

I am unable to get changes to the collection model to reflect in the api without updating EVERY single item in said collection. For example say I have a blog and I introduce a new field eg short_summary, the short summary field is saved successfully and is now in the ui but not in the api response. Not even a default value exists the field is just not included in the response. How can I prevent this behaviour is this intentional, using the latest version at this time 2.7.1. Clearing cache does not help