[REG 3.6 -> 4.0] Can't show disassembler

1. Have a simple program:

   #include <QCoreApplication>
   #include <QDebug>
   
   void func(){
       int s = 23;
       qDebug() << s;
   }
   
   int main(int argc, char *argv[])
   {
       QCoreApplication a(argc, argv);
       func();
       qDebug() << "Program ran forward.";
   
       return a.exec();
   }
   

2. Place a breakpoint at the call to func().
3. Run this in the debugger.
4. When the debugger stopped at the breakpoint, click the "Operate by Instruction" button.
   The editor won't change.

Instead, the disassembler view should be shown. With Creator 3.6 or even with my local build of Creator 4.0, this works correctly. With Creator installed from tonight's package, I can reproduce the problem.