Component-preload.js is a way to optimize the number of round trips the app has to load the view/controllers. Here, all the views/controller’s line of code are minified/concatenated into a single file component-preload.js so that all are loaded in a single shot! Whenever a request to load any of your view/controller is triggered, the code gets parsed from the component-preload.js instead of a XHR request. If the component-preload.js is not available in the app, then a request to the appropriate view/controller is loaded through XHR request for every view/controller. If a file/module is not found within Component-preload.js, then it will be loaded directly. As Vladimir said, the reason the files were loaded individually because framework could not find them in component-preload.
Problem might with prefixes/namespace, naming etc within the component-preload file.