This is a recent problem I just experienced. After I fill out the front and back and click add card, anki does not show me a new blank card. Instead the front becomes blank and the back is still the same, but if I fill in the front again it shows it’s a duplicate.
I can find the card I created in “browse” which means it’s been successfully added, but every time I add a new card I have the same problem. I have closed and reopened the app many times.