I have a last version of foodbook, and multibranch, and I desactivated all plugins for check the compatibility. And always see the thumbnails very big.
It’s a confliction your theme CSS with FoodBook CSS. We have listed this in our plugin update list. We will fix the issue ASAP and provide an update of the plugin on Envato Market (Codecanyon). You will get notified via email when the plugin update will available to download.