They've mentioned to me via the chat I had (near end of page 4 for screenshots), that they're aware of the issues and it is software and we should wait for an update. Although they didn't mention when exactly.
I am not even sure at this point that Samsung is aware of the issue. No official annoumcement on this topic.
I emailed sammobile this morning to get them to do an article and get in touch with samsung for a statement and they will update the post when they hear from samsung.
I've purchased the S9+ and received it on Friday (09/10/2018) as I've pre-ordered. I've noticed that HDR videos that I have on either the Micro SD card or copied to internal storage DO NOT playback the videos in HDR via the native video player. I have the S8 too and it is able to do so.
Obviously 3rd party apps like Youtube may need to release an update before HDR works there so that's understandable, but for the S9+ not to have this out of the box for the native video player is disappointing.
These clips are short 30 seconds recording on the Xbox One X and are full 4K HDR (Tomb Raider, Horizon 3 or Destinty 2 clips), and they play as they should on the S8 with 'HDR' showing when playing. However, on the S9+ it shows 'HDR' in bold near the title when the video plays, without the actual HDR enabled.
I've contacted Samsung, they've taken my details, serial number and IMEI number. They said they'll get back to me this week.
Just a heads up to everyone. I have the UK version, Exynos.
[Edit: 27/03/2018 - I do have colour grading issues, I was watching a HDR video at 1440p by Digital Foundry on YouTube and I can definitely see a sort of grainy presentation of dark and black areas of the screen. Black Crush is definitely present. Plenty of stuff on reddit and android central]
[Edit: I have chased Samsung and they called me back today (14/03/2018). They have escalated to their Product Support team as their Chat Team was unable to help and their other frontline support. They mentioned that they don't know when that team will get back to me as it's the first time anyone has raised it. I guess many people can't tell the difference and think HDR is working or it's actually working for them out of the box.]
Same here my s9+ is si bad in the night with black screen crush
I returnd 2 s9 Plus 64 GB exynos model with black crush now i have s9 Plus 256 GB with nog black crush its the perfect screen ever i think is a hardware defect for the 64 GB model.