This filter allows you to change the thumbnail size in the store listing.
This example sets the width and height of the store thumbnail to 100 pixels:
If the image dimensions you’re using results in a big empty space between the address and the other details, then the CSS code below will probably fix this.
Copy the above code and place it in a CSS file loaded by your theme.
If nothing changes, then make sure to clear the browser cache and the cache from any active caching plugins.
This filter is located in /frontend/class-frontend.php.