Some part of my progress on Japanese 1 course was lost

I’ve noticed that some section of the Japanese 1 course has lost some of the progress. Is this some planned work and will it be restored?

こんばんは Serge!
Sorry, we ran a big data migration to get rid of duplicate Learnables in our database, and it took a bit of time to complete, so your progress momentarily became invisible on items which have duplicates. Everything should be looking fine now.
Sorry for the inconvenience caused!
Have a good learning,