My C++ classes disappear after reopening the project. Why?

Hi, I am also in this situation. I start learning coding in c++ in unreal (UE5.5.1). So i did a first tiny code to move a cube in the scene in x axis, all worked properly, BUT, by adding a second class to code something else in the scene or after closing my scene and re opening it, my c++ class just vanished. After weeks of seeking on web to find a solution, i am still stuck in this really frustrating issue from unreal. It is a real no-go for me.
Even if i disable live coding etc etc i get the same result->class vanished.
I use microsoft visual studio 2022 with unreal plugin to get it working with unreal.
Finding a solution would help me a lot.
What the hell is the solution to this issue??
thks,