I was doing the first lesson in Conjunctions (Italian) and after I successfully completed it I couldn't advance to lesson #2 and lesson #1 still looked unfinished. I tried it two more times and completed it with some hearts left both times and I still couldn't go to lesson #2. I clicked the ''test out of this skill'' button and completed it successfully and now the Conjunctions chapter appears as learned on my tree but then I finished the first lesson in Prepositions (which is the next chapter) and the same thing kept happening. Before you ask, I'm not missing anything, I have been using duolingo for two months and just completed the German tree a few days ago and this has never happened before. Maybe it's just a temporary glitch but I thought I should report it anyway. Edit: Oops, correction, it lets me complete the first lesson in Prepositions but doesn't let me get past lesson #2.