I encountered this issue a few weeks ago and again today - I can't upload a new image into any journal Storymaps. It will let me browse and select a new image, but won't progress any further - just tries to load the image with 'Apply' greyed out. This can go on indefinitely. I can select and insert previously used images, and don't have any issues with uploading new images into my Storymap cascade. I'm on a Mac and have tried both Safari and Chrome. I don't seem to encounter this issue on PC.