Using medium size images

I have a similar problem. I can’t get the images to show bigger than 450px! If i put a value in the ‘Max width’ setting field it shows in the generated inline style but since it still reads ‘width: 450px’ it doesn’t have any effect. The actual size of the image i ignored and i have tried to put in higher values in WP’s media settings.

I’m having the same problem. Did anyone figure out what is causing this?