UPDATE: good news, it seems to be an slight API change, but not an attempts to stop 3rd party. So I could get it working again. Will push an update to the store as soon as possible.
It appears Garmin disabled access from ConnectStats again. As before I’ll remove the app from sales and turn off bug reporting until I can figure out the reason. I am sorry but at the moment I have very little time I can put into the app, so it may take a bit of time to get to the bottom of the issue. Also it is quite worrying that Garmin disabled it so soon, while it could be a coincidence and still a side effect of an API change, it’s also possible they just want to stop 3rd party app.
I will update when I can, sorry for the inconvenience.