I'm using Aquia Dev on Windows 10 for a local installation and after the latest Drupal 8 update (8.2 to 8.3), applying image styles to content now causes my images to fail to render.
Checking debug and the directory, the paths
site/MY-SITE/files/styles/MY-STYLES are correct and the images are there, but for whatever reason Drupal can't pull the images. The alt text is displayed instead. Image-styles that were applied to items before the update still render correctly, but changing the styles on the correctly rendering images thereafter again breaks them.
Most of the information I have found is geared toward changing "775" ownership on a Unix platform. I can't figure out what that means and translate it to a Windows set up.