I was doing my N4 normally and I usually do n4 kanji at the last out of all my schedules. Completed my n4 review and suddenly this happened. What does this mean?
if you learned a word that uses kanji it might not show up in the kanji form at first, after you learn the kanji the quiz will be adjusts from kana-> meaning to kanji->meaning (or whatever vectors you have enabled) therefore needing you to do them again.
depending on your settings the same might happen in reverse. learning a new word night unlock a new reading for a kanji you've been learning and that will suddenly add to your kanji reviews.
i highly recommend switching to kanji helper instead of doing the default schedules though, you'll only get kanji that you know vocab for it's much easier that way qnd you'll always instantly unlock all the vocab in kanji form!
i think the alt is just keyboard shortcuts maybe? I don't rly use PC renshuu too much.