The problem was a wrong defined setting option in dropzone.js
Previously I used:
$("#dropImage").dropzone({
url: "/upload-wp",
paramName: "file",
maxFiles: 10
});
And If maxFiles is higher than 1 the camera selection won't appear.
$("#dropImage").dropzone({
url: "/upload-wp",
paramName: "file",
maxFiles: 1 // <- solved the problem
});