Here is a couple of files I had issues with
Thanks a lot
Please excuse for the inconvenience. This is a bug and we will work to fix it.
Right now you can just remove the ".Mass" file extension from such files and open them.
To remove the extension pleasem, in Windows Explorer select file and press F2 - this will allow you to edit the file name.
In case Windows Explorer hides file extensions, please:
1. In Windows Explorer, choose Folder Options from the Tools menu
2. Click on the View tab
3. Find "Hide File Extensions for Known File Types" and UNcheck its box.