Can't preview a PDF file on Web browser

I have the same problem on most files now . INDD, JPG and PDF. Very frustrating as I cannot see if changes have been made to files by collaborators without downloading files to my laptop. On a Macbook Air, I simply don't have the storage to keep doing this - hence I work on a Cloud system. Tried to talk to live help and they kept insisting I could still access and download the files so they couldn't see a problem? When I click on a file to preview it comes up with the error message: Download Unavailable Something went wrong and we can't download this right now. Please try again later.

Please fix this! It increases my working time and is really inconvenient. I never had this problem until about 2 months ago.