Flexslider_picture doesn't render size other than smallest

I'm working on a few using flexslider_picture and I'm finding that I can't get the Views block that is placed on my home page (panel) to display anything other than my smallest image size. I've tried reversing the order of the breakpoints, doesn't do anything.

The strange thing is that in the preview of my views block when editing the view, it does indeed show up at the correct size, but doesn't via the rendered block in the panel.

I'm using AdaptiveTheme so I don't know if that has anything to do with it, but I find it annoying I'm unable to get this to work, so I'm reverting to just using "image" instead of "picture" as the formatter for the image field in my view.

Anyone have any ideas? This my second attempt at figuring this out and I really won't spend any more time on this since it's clear there's a bug or incompatibility somewhere.