Single-stepping in Operate By Instruction mode steps by source lines instead of instructions

When I stop my program in QtCreator's debugger, switch instruction mode (via the toolbar, menu item doesn't work), and then try to do single steps via F10 or F11, QtCreator jumps over dozens of instructions instead of single instruction — to the next source code line. Thus, disassembly becomes useless (unless you use kludges like breakpoint-continue-removeBreakpoint).