But there’s no option to do that on the Blog page. I wish I could paste in a screencap here. But all that’s in the Page Attributes widget is the Parent dropdown and the Order input box.
I’ve corrected the path (they didn’t get updated in the move). Thanks for catching that. Resized the picture to 250×250 and now it works. The others are only 230×230, but they look okay. I didn’t know about the minimum size, just the requirement that they be square.
As I said in my post, my images are square. This one in particular is exactly 183 x 183 pixels.