Items that were mastered and "go grey" again
Hi I finished a few topics and mastered them (got the golden cup, hurray:) ) Anyway some topics go "unmastered" after a while...and them I have to reamaster them again... any specific reason?
I believe Duolingo has changed the point requirements for mastering. Increased the required number of point in some of the skills to have them mastered. I happened to me as well, I think this is the reason.