Question for calibrators (DIY or professional). Does your colorimeter come into *direct contact* with the (LG C9) screen? The C9 panel gets rather warm and conceivably it could "melt" part of the rubber gasket on the camera end and cause an irremovable stain on the screen. This happened during a calibration performed by Kevin Miller on my KS9800, and the KS9800 doesn't get nearly as warm as the C9.
Golden Ear Triton Reference (pair), Musical Fidelity M6si, Schiit Yggdrasil, Oppo UDP-205, Emotiva ERC-3, LG OLED65C9PUA, Salamander Synergy Triple Unit SL20, Audeze LCD-X