Image uploading issue
I suggest you clear you cache and if not getting worked  I suggest install image style flush module and flush all your image styles.

Easiest way to flush image styles in Drupal 7.


  Image style flush Overview
  
  This module will allow Drupal to flush all image styles at once or
  flush each image style individually right from administrative
  interface. Features

Flush all image styles
Flush each image style individually

  
  Known problems

Private file image styles can't be flushed with this module.