Changed codex that prevents featured image updates?

I’m currently working on a theme that used featured images. After the 3.8 upgrade they are not working on my theme.

I did deactivate all plugins and switched to a default theme and the images appeared correctly then switched back and the images reverted to the wrong uploads.

Has the codex changed for featured images in 3.8?

Also, I checked the permissions on my uploads directory and everything is ok there. ???

Maybe I could look at the chanelog for 3.8 to dissect the problem.

Thanks!