Hi @HelenCooper! I can reproduce the crash you are seeing. It looks like the content in your story is arranged in a way such that there is just too much data being loaded at the same time for the amount of memory on a phone to handle. There's a very long 3D guided tour followed immediately by a slideshow with maps/scenes.
StoryMaps progressively loads the content on the page as the reader scrolls through the story, and this usually prevents crashing. However, when a lot of heavy content (3D is especially data-intensive) appears in the story in a small space it can sometimes still crash the browser on mobile devices, which don't have as much memory resources as desktops/laptops.
It sounds like this story is still in-progress so it's not a "real" or final story yet. In a typical story, we don't normally see a tour immediately followed by a slideshow. There is typically a section of text between them introducing the next set of maps or media. I recreated a test story where I have a 3D tour, followed by several paragraphs of text and an image, and then a slideshow and it doesn't crash on my phone. Can you try fleshing out your in-progress story with a bit more content to see if you still run into this issue? We'll also look into this on our end to see if we can optimize the content loading any more.
I'd also suggest using the explorer tour grid layout for any tours with more than about 10 points. Having readers scroll through a guided tour of 50 points is not a great experience because it involves so much scrolling.
Hope this is helpful!
Owen Evans
Lead Product Engineer | StoryMaps