I recently changed Microsoft Office out for LibreOffice. I set the defaults in Windows 10 for LibreOffice. I thought everything was good but come to find out Thunderbird would not open any .doc or .xls files. Even in Thunderbird I had the defaults set for LibreOffice. For some strange reason I had to set it using the file paths of the exe files. Thunderbird listed LibreOffice as an option but that did not work. It was a strange bug but at least I figured it out.
I wish more people used open source instead of giving their money to Microsoft.