pdf file download problems

I use the Adobe Creative Cloud file storage system to store and also share pdf files with my customers. When I need to share a pdf file, I create a link for the folder containing the correct pdf files. Then I paste the link to that folder into the body of an email that I then send to the customer. Often I will paste several different links into the same email. Normally, when a customer downloads, they simply click on the link, then they are directed to the folder contents. They then click on each individual file within the folder...on the next page there is a download drop down menu button at the left of the screen.....the dropdown menu normally give 3 or 4 options to download as: PDF, jpg, png and ease. For some reason the last week, at least 50% or more of my customers are not able to download.... they are telling me that the drop down menu does not give them the pdf option. I talked with Adobe customer support but the lady didn't seem to have the foggiest idea why this was happening or how to fix it...she said she would look into a solution and call me back but she never did. This happened about a month ago too and the problem seemed to correct itself a day or two later.... and again no one at Adobe could tell me what was up or how to fix the problem. Anyone out there experienced anything like this? Or maybe I am the only one using this service to share PDF files?