"Clear overlays" doesn't clear Canon overlays in external HDMI after startup.
Canon overlays will be seen in HDMI display immediately after startup until ML menu is called. After closing ML menu overlays are invisible. Issue does not appear in camera display.
Reproduced with 550D, 650D, 700D and various builds (Nightly and lua_fix, for example).
Not reproduceable with 7D and EOS M.