App stuck on welcome screen

Hi there!

I’ve used this app for a bit now, really love it. Tonight I’m trying to set it up for my mom, as she’s learning English, but the app is always stuck on the welcome screen. If I open her account on the web, it has the correct progress saved. If I open on the app (iOS), it sends me to the “Welcome to Clozemaster, choose a language” screen no matter what I do. The language pair she wants is to learn English from Chinese. Curiously, everything works if I select a different language pair, it seems we just can’t select this particular one.

Help? Thanks in advance.