Hello and welcome to JustAnswer! My name is XXXXX XXXXX I would be glad to assist you with your issue today. Please note that I am in eastern time (UTC -5:00) and am generally online between the hours of 10 AM and 4 PM and some evenings between 7 PM and 11 PM.
If the user who cannot see the file presses F5, it will force refresh the folder listing. They should then be able to see the file.
Thanks, XXXXX XXXXX give that a try.