Pictures Fail to Display in Posts

Windows 11 patched up to date; Edge browser

I frequently create scheduled posts consisting of a landmark, a small amount of text, and a 1,365 x 1,024 png image. The images always show as having uploaded correctly in the window where I create the post. Many of them display as blank rectangles in my feed. I'm attaching images of what I see when I create the post and what it looks like in my feed. I have verification that other users also see blank rectangles instead of the intended images.