Square and rectangle grid styles aren’t working

To create square and rectangle thumbnails, WordPress crops images when you upload them to your website.

You should use high resolution images. Default square thumbnail size is 600×600 px. Default rectangle thumbnail size is 600×400 px. So for example if you upload a 300×400 px image, square and rectangle thumbnail options will not work…

If you have a lot of images in the WordPress Media Library and if you don’t want to upload them again you can use the following plugin to regenerate all your image thumbnails in a few minutes.

Upload the following plugin to your website;

Regenerate Thumbnails Plugin

Using the Regenerate Thumbnails Plugin is so simple. Just activate it and click “Regenerate All Thumbnails” button. Plugin will regenerate all your thumbnails (They must be bigger then 600×600 px).