P: Strong Magenta cast in very raised shadows. Phase One IIQ files.

Hi, I'm giving Lightroom a try after years using Capture One. I've been doing some strong light still lives using Phase One's Extended capture, which adds 3 stops of dynamic range, blending two exposures in camera, which can give very dark files when exposing to highlights. The shadows raise fine in C1 but are turning magenta in LR. I haven't tried non extended capture files in Lightroom yet as I'm most interested in making use of the 18 stop (it is said) extended capture files. I've attached a screenshot which doesn't render the HDR the file was developed in, but shows the magenta cast which happens mostly in the corners, which is interesting, as if it were a lens cast issue... but the lens is a 90mm Rodenstock on a BSI, I think it's called, sensor which generally doesn't require a lens cast correction, but maybe a LCC would help in this case, but Lightroom doesn't offer LCC that I know of so I don't know how I would use a lens cast corrected file made in Capture one in Lightroom as the correction is in the accompanying metadata file, xmp or whatever, not in the RAW file... I sort of don't think that's what the problem is though but I'm not sure...