Hi, I'm having this problem using hlg3 in a Rec.709 color space in an A7iii - found this thread while trying to fix it. Turns out there's a bug in FCPX 10.4 that causes it to pick the wrong color space for some clips - the fix is to go to the settings tab in the inspector and select Rec.709 in the "color space override" drop-down. Sorted it for me :0)