Yes, I can see the same problem on both Windows 10 and MacOS. It seems specific to CR3, certainly CR2 is not a problem and nor is DNG (though I haven't tested other raw files types).
So I would agree that it looks like a bug, the workaround for now would be to rename the downloaded file to add the file extension (but not a great solution if downloading a lot of files).
Updates to the Adobe Photography Products were released on June 13. The update contains a fix for this issue.Please download and the latest version of your application via the Adobe Creative Cloud Application or your respective device app store.
If you do not see the update (Mac and Win) you can refresh your Creative Cloud App with the keyboard shortcut [Ctrl/Cmd]+[Alt/Opt]+[ R ].
Note: App store availability can take several days for the update to appear and be available.