This is a problem which has reared its head before. I am experiencing it across a number of sites all upgraded to 3.4.2 ... some with completely fresh installs, and ones upgraded, or transferred from one host to another.
Problem is not plugin related as the latest example to do so uses only Akismet.
WordPress is rendered unreliable for clients to use.
• All uploaded images exists in the wp-content/upload/ folder.
• All uploaded images render in published posts even though not appearing in Media Library
• Settings > Media > Uploading Files > Store uploads in this folder is default (also tried empty.
*BUT* either all images or, randomly, old images but not new images disappear from the
• Admin > Media > Media Library, or
• Admin > Edit Post > Add Media
Any ideas how to knock this one on the head?
Previously unanswered similar posts from others include: