Missing feature of Mix on Photoshop Express

I just bought my new iPad Air. When I restored the data from my old iPad mini, the "Mix" feature was missed. Even I tried to login again and again, and press the "restore purchase " button for many times, it is still disappearing.

My premium subscription is expired soon, I really love to use the app for my creation but if I cannot use the mix function, I will cancel my subscription and find another app to replace.