If you have already changed a value in the Editor details panel, as you mentioned, the editor will mark this variable as “dirty”, and it wont update the value from c++ anymore, no matter how much you change in the constructor. What will count is what you set in the Blueprint Class for now (I’m actually speculating it’s treated that way, but the results are that)
To solve this, if you see a little yellow arrow next to the variable and click it, it will set things back to normal for you. (what you are actually doing is reseting the value to default - c++ constructor)