Media Resizing Issues!! Problem with cpanels maybe?

Hi!

I am using versions 3.2.1, 3.3, and 3.3.1 on mulitple different sites. Problem is, the Edit Image functionality does not work in most of our sites. (The section where you can change an image size from thumb to large and vice versa)

We always thought it was just a malfunction in WordPress. Now I’m trying to narrow down why it may not be working on some but works fine on a few others. Finally realizing my common factor is that the sites working are on one Cpanel server and the site not working are on another cpanel server. Both of these servers have mirrored settings, so I don’t know what could be different?

Does anyone know if there is a certain requirement for this Image Sizing feature, that we may have blocked in our server?? Or how we could get this working?

Thanks so much,
Lindsey