FYI – After upgrading to WP 3.9.1, I could not see the uploaded images in the library, even though they were visible in the edit mode. I deactivated and even removed all plugins, and that did not make any difference. Also changed all permissions to 777 on advice of my hosting company, again no difference.
Even after restoring with a previous version, it still would not work. Finally, I had to delete the database on my hosting site and do a fresh install with the previous version to be able to upload pictures again.
Just thought the techies should know. Let me know when they get it fixed.
I am having the same problem with images not uploading either with the add new media feature or NextGen plugin. I have even tried restoring to a very old version of WP that used to upload images, but does not now. I have tried deactivating all plugins and updated to WP 3.9.1 latest version.
My IP hosting provider told me to change the permissions to 777, no luck there either.
Any insights would be greatly appreciated, been hacking away at this for days.