This usually means that the activity file is corrupt and Garmin Connect does not accept it. Connect the watch to a computer, and try to upload the corresponding file manually.
If you get any message other than "import complete," then there is a problem with the file. You can try to repair the file using 3rd-party tools, such as FIT File Viewer or FIT File Tools. Both of these run in the browser and require no additional software. If you're still unable to import the activity into Garmin Connect, attach the file to this thread. We can take a look to see if it is repairable.
Zip the file, then in a reply post Insert>>Image/video/file>>click Upload>>browse for file>>OK.
Or upload the fit file to a reputable file sharing service, such as OneDrive, Google Drive, Dropbox, make the file public, then paste a link to the file in your post.
The problem is that I have a Macbook and it doesn't show the Garmin as a device. When plugged in it simply charges, I cannot see the files in it. I've also tried with Garmin Express but it just takes me to the Garmin connect web page.
