Please deactivate all plugins except this one and change theme to default theme. Then try. Let me know.
If still have same problem please give me access to your website so that i can try to find the issue.
1. give me admin details which have no issue
2. give me that user details which have issue
3. give me ftp so that i can enter some debug code (you can create a ftp account which have only wp-content access)