Hi Angelo.
I am having the same problem with Redux Framework. I loaded the tool through my functions.php instead of using composer, but I got the same result as you.
Taking a calm look at the problem, what’s happening is that the Redux base URL is pointing to a parent folder of redux-core folder, so it doesn’t find the assets.
As I understand it, this error is on line 250
of the class-redux-core
file:
self::$url = trailingslashit(dirname($theme_info['url']));
The $theme_info['url']
points to the redux-core folder, but by wrapping this variable in dirname, it points to the redux-core parent folder.
Although it is not recommended to change the assets in the redux-core folder, I changed it as a matter of urgency to proceed with development. I’m going to open an issue in the repository to validate and see if it’s really an error.
I changed the line to:
self::$url = trailingslashit($theme_info['url']);
And everything went back to working normally.
I hope I’ve helped.