Debugger: Cannot hit (C++) breakpoints when using Desktop kit on macOS

Steps to reproduce:

• create a Widget application from template (or Quick Application)
• set hittable breakpoints
• start debugging (if Quick Application had been used, ensure you have Qml and C++ debugging enabled)
  • debugger starts
• try to hit any of the breakpoints

Current result:

• hitting a Qml breakpoint works, but I cannot stop at any of the C++ breakpoints
• using an Android kit made both work for me (on device/simulator), but I didn't manage to get the same app stopping at a breakpoint using a Desktop kit

Attached Debugger Log of 2 runs (once with Qt5.6, once with Qt5.9)