Turn on the HDR option on Windows to check it out, and don't forget that all of TrueTheater video enhancements should be OFF in powerdvd.

Quote Turn on the HDR option on Windows to check it out, .

Can't do that. My videocard does not support HDR.

My playback result is that both upper half and bottom half have steps in powerdvd.
And, the steps at 8-bit bottom half is more noticeable.

The result is the same in powerdvd, potplayer and VLC.
No issues.

Quote My playback result is that both upper half and bottom half have steps in powerdvd.
And, the steps at 8-bit bottom half is more noticeable.

The result is the same in powerdvd, potplayer and VLC.
No issues.

This means that your system cannot output 10bit colour right. 10bit gradient should not have steps. This is one of the reason why 10bit was invented.
On my system i see 1 or 2 bandings, but no steps (MPC HC).
Here is another test pattern
https://1drv.ms/u/s!AtKqx5PpFumGgvcICdHmAlfkT3_3eg?e=VTvBbG

I'll contact Cyberlink support and report back here later.

CQ2.0, what is diagonal of your TV? Maybe you see steps because of huge display. There is 256 steps in 8bit gradient and 1024 in 10bit.

Technically, there are always steps in detail no matter it is a 10 bit video or 8 bit video, but it is easier to catch the steps in a video that is produced in 8 bit color depth.

55" 4K HDR TV shows it fine in powerdvd as other players:
The steps at upper part is less noticeable, and more noticeable at bottom part.

But, personally, I don't think there are any values to test this specific clip that oddly encoded 8 bit and 10 bit content into single one.
All the videos are already compressed and post-processing during the production phase, the file here is not exactly same as what the original image looks like at pixel level.

We use powerdvd to watch movies but not for scentific color research or testing purpose.
GPU driver affect the final color rendering results between different software player combinations as well.

Quote
But, personally, I don't think there are any values to test this specific clip that oddly encoded 8 bit and 10 bit content into single one.

The second test pattern made by Spears&Munsil. I think this guys know what they are doing
http://spearsandmunsil.com/about-us/

Cybrlink support answered that 10bit color supported only with hardware decoding and HDR. With software decoding there will be only 8bit.