@OwenGeo
Hello, I'm a student looking for a solution to this same problem, months later (October 2022). I'm using chrome, I've checked that my browser does support WebGL, but the express maps (tour maps also malfunctioning) has only successfully loaded once, but did not save. I tried something suggested on another community post and opened up 'developer tools' under the chrome three dot menu, then clicked the console tab, went back to StoryMaps, reloaded, and it worked! For a moment.... I'm not a developer but I could see that it said WebGL lost... so I suspect it has to do with that. However no matter how I tried to repeat the process or get anything to save, it won't. Is there another solution I don't know about? I'm a student and falling behind because of this issue. Base map won't load, search bar doesn't work, nothing to click or do. Same for manual Tour Map.
Thanks!