I had this issue since I got Windows 10 on a 4K screen notebook: most of the apps seemed to have correctly displayed their content considering the DPI setting (250% by default in my case) but a few – specifically, Facebook and WolframAlpha – failed to do so and displayed elements as if there was a standard 100% DPI value set on the computer.
While I was testing another desktop app and needed a lower resolution, I tried temporarily downgrading to HD (instead of 4K), operation which also changed the DPI setting to 100%. On HD mode, of course, everything went fine for the Windows apps too, as I expected.
Then when I switched back the screen resolution to 4K (and the DPI setting went back to 250%), I was surprised to see that the Windows apps work fine too, considering the updated DPI value. I’m not sure what happened or how the individual app issues have been resolved this way, but I’m almost 100% positive that there were no app updates installed in the meantime since my tests have only lasted for about 10 minutes, and then the resolution got back to the original value.
Note also that this might also be an Intel graphics issue, since to change resolution I created profiles in Intel HD Graphics control panel, rather than simply changing the resolution from Windows settings (but I’m not sure if this had anything to do with the fix).
Anyway, if you have similar issues yourself, try changing the screen resolution, rerun the apps, then change the resolution back and the size of the elements displayed by those apps may be eventually fixed!