As of March 2nd, 2020, the Instagram platform will be deprecating its API. This will directly affect the Instagram feed section in all WordPress & Shopify themes. Read more on how it affects your theme here: https://fuelthemes.net/important-notice-instagram-feed-removal/

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Post Grid and Post Grid Carousel Image sizes

Goodlife theme requires that your featured images are at least 800x700 pixels in size.

Also, you can always use https://wordpress.org/plugins/force-regenerate-thumbnails/ plugin to regenerate your post images.