Preview image missing on captured image upload on iPad

Observed in Safari on an iPad Air 3 running iOS 13.3: upon the completion of an image upload (the first attempt for that block), the image block's preview changed to an empty box rather than to a preview of the uploaded image. Upon uploading a second image, everything worked as expected.

To reproduce:
Not sure, requires further attempts

Expected:
After uploading an image to an image block, the preview would be set to the uploaded image

Actual:
The image block preview was a small empty square