I was a ways through the Admin Trailhead.  After submitting a challenge and error was encountered (sorry I don't remember the error message).  I logged out and then logged back in.  After logging in an error message was displayed stating that the trailhead servers had been overloaded and that I should click the refresh button.  I tried this several time, but to no positive avail.  Finally, I logged out and logged in again.  I was able to log back in, but all of my previous Trailhead progress was gone as if this was a totally new account.

I just completed two new badges this morning. I started with 5 badges, including two "Quick Start" badges, and completed two modules of the Admin Beginner trail. The new badges are displaying on my profile, but the two "Quick Start" badges are gone:


However, on the home page, it stills says that I have 7 badges (although there are negative two active modules!):



And when I check on those Quick Start modules, I can see that they're checked off:



This appears to be a bug and not user error. Anyone else seeing this? I'll provide an update if the badge count reconciles.