I have face one issue when user wordpress media up-loader fronted side. Also i assign upload file permeation for that user role. The same thing working my local server to. But when i move on live server when i click on upload button media upload popup open. When i select file for upload its give me error "An error occurred in the upload. Please try again later."
When i refresh page user logout so this happen. so i think when i try to upload image user logout auto.
On live server : Wordpress version 4.7.3 / php version 7
Local server : wordpress version 4.7.3 / Php Version 5.6.24