Visual Composer is one of the best drag and drop page builder plugin. Whenever you cannot edit things both at front-end and back-end editor, please follow the below steps to fix the errors and get it running as it should.
STEP 1: Enable Visual Composer
- In WP admin panel, navigate to Visual Composer > Role Manager
- Choose Post Types tab and mark all tick boxes
STEP 2: Create an google map API key
- Access here to get an API key
- In WP admin panel, navigate to Theme Setting > General > Map google API Key
- Input the key you have just created