It's probably the file size Texas_Sue, it took me months here before I figured everything out and I'm somewhat techie, unfortunately I don't have a smart phone and can't help too directly.
Try putting your picture on the website below, reduce the file size, and chose the download option.
https://www.reduceimages.com/
Because of my vision issues, I have my default set in file manager to large icons, I reduce my windows screen to about half my monitor. My file manager is set to come up on top, I simply select and drag the picture from my camera/system to the spot on the website, then I re-maximize my screen.
In the picture above, I reduced the visual size to 60% and the Quality (File Size, that's the important one) to 80%.
Then, when you are in the advanced options here, when you get to the Browse option, go to your download folder (it's probably a pre-selected option even). If you are having problems getting to that advanced screen, try holding down the CTRL button on your keyboard while you are clicking the "Manage Attachments" button.