Gui loadFromFile fails on linux without error message

I am porting an application from mac to linux. It crashed on linux and qt creator without giving any error message, unless

17:27:09: The program has unexpectedly finished.
17:27:09: The process was ended forcefully.

I have start removing things one by one until I have found the line that breaks:

gui.loadFromFile("details/scene0.json"). the file it is where it is supposed to be, and in any case if I give a wrong file name, I see an error message:

ofLoadJson: Error loading json from data/details/Scene0deta-l.json: file doesn’t exist

So I assume that it founds the file but it fails when reading it or when it initializes the GUI.

I also have already tried to put a breakpoint to:

void ofxBaseGui::loadFromFile(const std::string& filename){
	auto extension = ofToLower(ofFilePath::getFileExt(filename));

in ofxBaseGui but it does not stop.
Any suggestion about how to fix this?