Those pesky iPhones 7/8 '18
iPhones have a new feature: as of iOS 11, they don't save photos in the familiar JPEG format. They save them in a new format called HEIC. It's very nice. Web browsers can't handle it. Until today, OPW couldn't handle it either.
However, Rabbit was kind enough to point this out with some useful pointers in the right direction, and I found tools to convert HEIC to JPEG.
So, please enjoy the ability to once again attach photos to your OPW posts from your iOS devices.
For those who haven't tried it before, look in the lower right corner of the editor, where you see the words "Add Media." To the right of that, click the little picture icon, then the browse button that follows.