This could have a big number of causes. Following the main points to check if the plugin has been setup properly:
- Grids/galleries are shown ONLY if all the thumbnails are loaded properly.
--- On Media Grid be sure you have set the featured images for all the items
--- On Global Gallery be sure all the selected images are displayed properly in the builder - You have to be sure Easy WP Thumbs is setup properly in the plugin settings (remember you can try to use also TimThumb)
- (only for Media Grid) If also Timthumb doesn't work, you can switch to WP thumbnails
- Grids/galleries are completely managed by javascript before being displayed. For this reason if you have javascript issues in your website, they can block everything. A good practice is always to take a look at the browser console, it can avoid you many time losses.
In most cases the Easy WP thumbs forcing mode will solve your server restriction problems.
You find that option in plugin settings - advanced block.