HDR Issues When Exporting

I'm fairly new to using FCP, for a long time, I used iMovie.

When I imported a few clips in 4K HDR into iMovie and then exported the final video, they would have HDR. Yet when I do the same in FCP, the colours in the exported vid dull and muted. I use HEVC (10-bit, HLG, Dolby Vision 8.4) when exporting. Also, I noticed that if I export using HVEC 10-bit, the colours look great but I think they're in SDR.

Is there something I'm doing wrong? Or is there a setting I haven't turned on?