If this is happening to you, it's likely one of two things:
- You are using Wordpress Multisite and have "Network Activated" the Image Intense plugin. For whatever reason, this causes a conflict which prevents the custom module from displaying in the builder. The simple solution is to network deactivate Image Intense and activate it on individual site(s).
- You've just accidentally overlooked the custom module in the builder. Look for the following icon inside the list of modules: