It seems that they made it stable now (or for now :-) but they made minor changes that required an update to my apps. Get the Uploader for Garmin 8.4 or Sportablet 9.4 to solve upload issues (at least while they're still working / until they change it again).
If you still have problems after upgrading my app:
1) check that your password complies with the new garmin requirements etc (see my previous post for details).
2) check that you can indeed upload files, either with your computer or by exporting the file from my app and uploading manually to garmin connect. If their website becomes erratic again, I can't fix it from here.
3) after that, get in touch from the contacts page as I may have to see a log of your transfer to garmin connect (don't send me a transfer log while reading from the watch as that doesn't really help :-)