I've been working on Gaelic for a couple of weeks. I started as someone who already had a little knowledge and have been trying to do some every day. Now, however, sections I had completed indicate 0% - even the introductory section came up yesterday as incomplete, now today the phrases section has 0% although I had finished it.
I thought I was doing fairly well, not I'm just completely frustrated, having to repeat simple phrases I had done already. Losing motivation on it, I'm too busy to have to do everything twice!
It is still happening - much of the work I have done in the last few sessions seems not to be recorded. This is really frustrating - I had finished 2 sections - phrases and food, of which one now says 1% complete and the other 0% complete. I already had to go back and re- complete the introductory section which I completed right at the start.
I'm guessing this is because of the crowns. So you can get up to 5 crowns per skill. If you complete a skill once, it goes up one level, and you get a crown. Read more about it here:
Don't worry, you haven't lost any progress. I would recommend completing as much of the course as possible up to the 1st crown. If you start getting confused, redo some of the skills you've done already. Hope that helps :-)