Zero App Field Image not an Option in Default Sharing or JSON-LD

Hello, I am using a field image in my Zero App posts that I want for social sharing and my schema markup. I don't want to use the default image. Why can't I select this in the field picker when generating the placeholders in the global settings? I really need all the fields to be available in there.

Can you add this for me until you can update it? Or explain why it's not possible? It will be an issue if I can't use this field for those settings. I need large, full-resolution images, and my category page will be 25 MB if I use them as the default.

Thank you

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