Changing Profile Picture Problem

Hi. I have been having problems with changing profile photos for subscribers. It works fine for admin and we can change profile photos without a problem.. When a user goes to the profile page and clicks on the setting wheel everything works fine. However when they click on the profile photo area, it very briefly flashes up the change profile photo / remove / cancel menu, then redirects to the profile page again. Cover photos can be changed without issue. In the back end it is set to allow profile pictures to be changed for subscribers. My site hosts have tried all the suggested options and more, but still cannot resolve the issue. Memory limit increase, Imagick & GD PHP extensions are installed, temp directory is unrestricted. Mod_Security was tested but made no difference. Really not sure what to try anymore. Can you help please?