Different behavior while debugging than while running - c++

Question

I have problem with running and debugging my program.
The thing is that when I run my program by 'Run' there is some bug, but when I'm trying to debug it, then it works fine.
I don't have a clue how to solve that.
There is link for short video: Video presenting problem
While running 2 sectors don't work, while debugging everything works fine.
I'm using CLion.
I find that different behavior happens in this function(it's only a piece of code, because whole project is quite big):
LevelSegmentCords* Space::findPlaceForBruteForce(int x, int y, int z) {
LevelSegmentCords *segmentCords = nullptr;
int i;
for(i=0;i<this->getHeight();i++){
int lastX=0,lastY=0;
int checkerX=0,checkerY=0;
do{
segmentCords = levels[i].findFreeSector(x,y,lastX,lastY);
if(segmentCords != nullptr){
segmentCords->setStartLevel(i);
for(int j=0;i+j<this->getHeight() && j<=z;j++){
if(!levels[i+j].isSectorFree(segmentCords->getX1(),
segmentCords->getY1(),
segmentCords->getX2()+1,
segmentCords->getY2()+1)){
checkerX = segmentCords->getX1();
checkerY = segmentCords->getY1();
}
}
if(checkerX != lastX || checkerY != lastY){
if(checkerX + 1 < this->x){
lastX = checkerX+1;
lastY = checkerY;
}else{
break;
}
}else{
return segmentCords;
}
}else{
break;
}
}while(true);
}
return nullptr;
}
This function should basically find place to put there cuboid.