Can't get my mobile version backgrounds to behave

I’m working on my portfolio site ( - check it out!) and I’m having some problems with the mobile version. I can’t get my background images to behave. When I use chrome emulator on any of the phone options, it switches over to my mobile background images no problem, but I can’t get it to work on actual mobile devices. As far as I know I’m using all the appropriate media queries and the like. The column rearrangements that should happen at that screen width do, but the background images do not. Anyone have suggestions for resources to troubleshoot with?

In portrait view on my phone it looks like there is no background picture on the top section, but I think that is because the photo is pretty solid black in the center. When I rotate to landscape view, I can see a bit of the wooden post.

Yeah, that’s the issue. It should be switching over to a different crop (and lower filesize version) of the same image based on the width of the screen. All the developer tools I’m aware of that emulate screen size for phones seem to do it (as does reducing my browser window to approximate phone size) but on an actual mobile device it won’t do what it’s supposed to. I’m stumped.