It’s a limitation of how Google Docs stores files and how Google Docs offline works.
You’re thinking that gdocx files work like docx files and Google Docs Offline works like Word. In that you could double click a gdocx or gsheetx file and have it open in Google Docs offline.
None of it works like that. Google Docs offline isn’t like a normal application. It won’t open files off a double click. You need to use Google Docs Offline to manage and open the files.
There is nothing oDrive can do to resolve this as it’s a limitation with Google Docs. oDrive isn’t intended to manage Google Docs files like other files. Now, if you use it to sync normal docx files and open with with Word or Libre Office you’ll have what you want.