HLG clips are still not supported in Kyno 1.4. The very same version of the third-party-app Kyno used to repeat the Finder warning unsupported file type, unable to play back (or so), but now miraculously (just after a restart of the app) shows them, you could say reluctantly. And indeed, Finder / Preview / QT player now play back a greater variety of video files (they used to reject naked, unwrapped mts-clips, for instance), but specifically not some of the 10-bit GH5 files (and others). Since Yosemite, allegedly, the whole OS (and OiS) uses it as framework. You didn't mention if you edit with FCP, which uses AVFoundation.
