Images are not sizing correctly

All of a sudden images I insert into my blog posts are coming out square. I’ve changed the default behavior of the images so that they maintain their aspect ratio, but for some reason that request is being ignored on the current post I’m working on. Fortunately the other posts are still just fine.

Any suggestions? Usually in cases like this I “reset” the settings preferences. Even if a “maintain original aspect ratio” button were set I’d clear it, save, select it and re-save just to force the system to re-read the settings. However, I can’t seem to find the “global” maintain aspect ration button, all I see is one for the thumbnails.