I have some problems when uploading images from mobile clients using the desktop version. When uploading avatar images or new photos it seems that the upload is started, but the image isn't actually uploaded.

* With profile avatars, after uploading the .../profile/avatar page is displayed again but with no content (blank)

* When uploading in the Photo section, an error is displayed, that the uploaded image is not found

* I have checked that the server directories are present and have the correct permissions (777)

* I have checked with debug mode, but no errors are displayed

* There are no errors in the server logs

* Upload from desktop web browsers work fine

* Problems have been encountered from iOS and Android devices, with various browsers (safari, chrome, Android stock, ...)

I'm using a fresh install of Platform version 1.7.1 (build 8274)

Any ideas where I could start poking around to solve this?