The issue of file extensions missing from downloads is caused by certain special characters being in the file name.
While our developers are aware of this issue and working to resolve this, they have advised that you will need to remove any special characters from file names and then upload the new files and change any download links to point to the new files.
Common special characters such as _ or - do not cause this issue.
File extension missing from downloads
This article explains what to do if files from your site are being downloaded without any file type or extension.
Written by Cristiana Ghinea