HP Prime - problem with Solve App

[MarkF]

Hi everybody, I recently updated my hp prime's firmware and have since been having trouble with using Solve app the way I used to. I used it mainly to solve (non-linear) equation systems e.g 4 eqs involving 4 variables and putting appropriate seed values, then I was given the solution to the system. Now the message "cannot find the solution" keeps appearing no matter what the system is (tried very simple ones to check if I was mistaken). The only way I can use the app now is to check equations with just one variable. Another thing I noticed that is different is that in the Plot view now appears a message "check exactly one equation". I wonder if anyone could help with this problem. I thought of going back to the previous firmware version but I don't know how to do that if possible.

I hope you can help me soon, I'm an engineering student and the app used to be really useful to me. Thanks for your time!

Mark