Insert All- Red X on Photos

When I upload multiple images to a blog post, I use the PS Insert All button. This has always worked fine for me, until my last 2 blog posts (I believe this is when I upgraded to version 3.4, but not sure). Now, when I insert images with the Insert All button, they show up blank with the little red x. However, when I go back and insert them one by one, they show up fine. I’d like to use the Insert All as it’s a big time-saver. I am using a Pro-photo theme. https://www.annewilmusphotography.com

Thanks!