Tim,
The following link points to a fish picture that was uploaded to google drive spreadsheet using your image upload example.
" https://drive.google.com/uc?export=view&id=1X1v2c17znTA5GcVCr6u49LXXPmalaX9b"
over wifi it loads just fine. over cellular network it does not load. Can you tell me why this is happening? File size is 24KB.