Apologies for the late response and also for the frustration & difficulties you faced with the new Adobe Express. Do you still see the issue of the file not opening? Are you getting any error messages? Which browser are you using?
Have you tried using the other suggested browsers (Safari, Microsoft Edge, and Google Chrome) to see if it makes a difference? Try clearing the browser's cache and cookies to check if that helps.
Also, try restarting your computer.
From Windows browser: Ctrl + Shift + Delete
From Mac browser: Cmd + Shift + Delete
Hard refresh: Ctrl / Cmd + F5 or Ctrl/Cmd + R.
Please let us know if this helps. Also, let us know what is the file type format. Please help us with a screen recording of the workflow so we can investigate further.