HDR not working on Mac.

I've seen Windows users complaining about HDR not working correctly and I'm not having anymore luck on a, Mac.

It does funky things to the game application, both on my iMac's display and my second display, a 55 inch 2018 LG 4K TV that does support HDR. Stuff like freezing upon start up or just crashing the application atogether. Even when I can get the game to launch and play with HDR on everything is so dark it almost looks like a completely black screen.

The specs are as follows:

27" 2017 5k iMac running Mac OS Mojave 10.14.3
3.8 GHz Intel Core i5
16 GB 2400 MHz DDR4
Radeon Pro 580 8192 MB

Unchecking the HDR option in the Mac start up dialogue appears to make the game run like it should without any graphical issues.

So is this an issue for everybody, both Windows and Mac, or should this be working correctly for me?