gashacon

Les Bessant

WordPress 3.5 introduced a new feature – when images are inserted into posts, the title attribute is not included in the image tag. This was done with the best of intentions relating to accessibility, as documented on <a href="https://core.trac.wordpress.org/ticket/18984" rel="nofollow ugc">Trac</a>
Unfortunately, this causes problems for some Lightbox plugins, quite apart from stopping image tooltips from appearing.
This plugin hooks into the media_send_to_editor filter and inserts the image title into the html inserted into the post.
The original author, LesBessant, sadly passed away and in the meantime the original plugin was closed. I plan to keep the plugin up to date whenever an update breaks it.

IMG Title Restore

Restores the title attribute when images are inserted into posts

Taylor Callsen

Automatically populates Alt and Title tags for images featured in posts and pages, pulling directly from the values set in the Media Library. This makes it easy to manage your image metadata centrally in one place (the Media Library). Plugin also supports the ability to override the Alt/Title tag Media Library values by placing an Alt/Title tag directly on the attachment in the WordPress WYSIWYG Editor.
Tag population only occurs when viewing the post or page, and does not occur in the WYSIWYG editor.

Auto-populate Image ALT Tags from Media Library

Automatically populates Alt and Title tags for images using the values set in the Media Library.

IMG Title Restore vs Auto-populate Image ALT Tags from Media Library