I am having a similar problem. Here are the details.
I am relatively new to WordPress. As per the documentation and a course I took on lynda.com, it states that multiple versions of images get created when an image is uploaded, based on image sizes specified in Setting->media. I however see just the original image getting uploaded. I have checked that there is a single image (the same one I uploaded) in the "uploads" directory. Multiple image sizes are not being created -- so there is no <image name>-150x150.jpg etc. being created. Also, when I insert the image into a post, only the "Full size" option shows. There is no option to select "Thumbnail" or ""Medium" size etc. Following are the details regarding the site.
- I have version 3.5.1 installed (I had the problem with version 3.5 also)
- I am using the twentyeleven theme (although I have tried a couple of other themes and still have the problem)
- The only two plugins installed ar the default one (Hello Dolly) and Akismet, neither of which is activated
- I have a bare-bones site with minimal additional stuff and still have the problem
- I am hosting my site locally on my system at this point since I am still learning
- The memory_limit in php.ini is set to 256M
- The image sizes I have tried are both, lower and higher than 1MB
- The image property shows the image as: 2048x1536pixels
- I have tried modifying image sizes under Settings->Media, but the behavior is still the same
- I have tried adding images directly into the post, or just adding images via the Media Library, but the behavior is still the same
What am I missing? Any help is much appreciated as I have been struggling with this for a while now.