C++: ++x vs x++ in the Challenge Section of the Sololearn App

Question

Its clear x++ first uses the value x and then increments it by 1 and ++x first increments the value x and then uses it. However, solving several simple tasks in the Challenge Section, I noticed that all my answers to the questions about the increment in C++ were evaluated as wrong. Can it be caused by some internal app error? Consider the following:
int main() {
int x = 12, y = 6;
cout << ++x % --y;
return 0;
} Expected answer: 3, App Playground says "agreed", App Challenge Section says "no".

Answer 1

Some questions in challenges have wrong answers. We should screenshot them and report them to [e-mail] so that they will be taken care of.