I'm not a color scientist or even a professional calibrator (or even a TV reviewer! lol), but I'm very curious and passionate about the subject. So what I will say may not be the absolute truth. I understand that both the iterative method of CalMAN and the faster and more modern method of LightSpace are based on a RGB tristimulus system, while the current OLED display LG is a WRGB which, in most cases, continues to be a tristimulus system but with the use of an unfiltered white subpixel instead of one of the classic primaries for reasons of efficiency and consumption. Both software know where they need to go, but CM is like a driver without a navigator or a map, he will try all the roads before he gets to his destination.
The fact remains that, as the internal video pipeline is composed (3DLUT before 1DLUT), it is perhaps better to leave a unity LUT in the 1D slot or measure/create/upload 3DLUT directly from native gamut, subtract grayscale readings from 3DLUT and then measure/create/upload 1DLUT. Can you do that with CM?
TVs: Pioneer PDP-LX5090H, LG OLED55C8PLA | SintoAmp: Pioneer VSX-921 | BD Player: Panasonic DMP-BDT260EG | External LUT box: Entertainment Experience eeColor | Softwares: Light Illusion Lightspace HTP, Portrait Displays CalMAN Home Enthusiast 2018 R3, HCFR, DisplayCAL | Probes: x-rite i1 Pro 2 - i1 Display Pro OEM B-02, basICColor DISCUS | Test Pattern Generator: DVDO AVLab TPG