You can import from the activity list page... Look at the top right of your last activity and click on "ACTIVITIES" and then on the right side top of the list you should see " Import".
IDK but the file is just a .fit file...do different devices make it incompatible? I thought a fit file would work as long as the files were that format
Not sure but it could also be a corrupted file. You can find a few repair tools on the web or try to get a .TCX file and import that instead, I think it contains the same information as the .FIT files.
