My usual reason for my pictures failing is that the file size is too large, I have an old school digital camera. I go to this site to reduce the images, I just use their defaults and download the picture to my Download File.
https://www.reduceimages.com/
I have no affiliation to this site, it doesn't do much but it reduces pictures easily and quickly and without setting off my computer protections!
I use Firefox and I have a lot of browsing protections, and haven't been able to make the paper clip icon work for me. But here's a post I made using screen shots from my computer. If you go up a couple of posts from this linked one, there is more about the reduced images site.
Also, one post down is another image of the actual file browsing screen.
Bonnie Hunter's 2019-2020 Frolic Mystery
Edit: Doesn't navigate easily from that link. It is the Bonnie Hunter Frolic thread under challenges. If you start from the back and go back a couple of pages you will get to the other posts and discussions -- plus more help from someone else for another person. It took me a couple months to figure out posting on the old format -- this was just a couple adjustments once I figured out what my issues were! (Figuring out to extend the page to get to the upload button took me much longer than I'd like to admit...)
Bonnie Hunter's 2019-2020 Frolic Mystery