Gallery. When it first started, I was uploading photos to Facebook but some of them didn't show up and some of them were only half of the picture. When I went to Gallery the thumbnails showed up but when I clicked to open one, it would open but in a few seconds, disappear.
Now it working accordingly. 🤔🤨🧐😯 If you're still having issues with Instagram app, reach out to their support team directly.