Sorry to re-post this issue again, but the problem is real and now unacceptable after so much time it has been found, also due to the cost of the iOS App (24,99€).
The App crashes any time you insert a variable in CAS mode and press Enter, but also in algebraic mode when calculating e.g. a limit with a variable.
I have also the HP Prime Virtual Calculator for Mac OSX and it works well, so it must be a problem related to the iOS version of the App.
Please can someone in HP Calculators division solve this problem?
The App would be very useful but this problem makes it of little use and lowers the credibility about the HP quality: e.g. I bought the App to try the HP Prime calculator before buying one real but now I am uncertain.
Please note that I own an HP41CX, HP28s, HP71B, HP12C, HP48GX and it is the first time I see such an impactful problem from HP Calculators