Hi @DeeDesign,
Thank you for reaching out to us. I tested the Grid plugin (v2.7.3) locally and it works fine with WordPress 5.3. Ensure everything is up to date according to our version compatibility list at https://theme.co/apex/forum/t/troubleshooting-version-compatibility/195. Please follow the best practices when updating your theme and plugins. See https://theme.co/apex/forum/t/setup-updating-your-themes-and-plugins/62 for more details.
The latest supported version of the Grid plugin is 2.7.3, to update the plugin, navigate to Plugins section and delete the Grid plugin first then go to X > Validations page the install the Grid plugin to get the latest version.
Also make sure the X and Cornerstone are up to date as well (X v7.0.4 and Cornerstone v4.0.4). If the issue persists then there might be a third party plugin conflict which could be breaking the Grid plugin, to test that try deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Let us know how it goes!