Suddenly, I can't insert a png into my Google Doc document. It used to work before, I'm sure. But now, whether I use Insert>Image or copy and paste, I just see a bounding box with a big exclamation mark in the middle.
It doesn't matter if I'm in Viewing or Editing mode of Docs. I'm using OS 10.11.6 and Chrome version 63.0.3239.84 (Official Build) (64-bit)