Buttons to go up or down a level missing!

So I’ve been using Memrise for half a year now to study Korean, and I’m currently at the end of level 2. I’m a premium user.

I ran into some issues and I was told to redownload and reinstall the app. Since I did that both the button to go to level 1 and to level 3 are missing.
As a test I’ve added Korean as a new language and the buttons were there but all my progress was obviously missing because the app thought it was a “new” lesson. Help please! I don’t want to have to do two entire chapters all over again due to a bug!