@cdu13a, here are the results from the tests. As you can see all of the 10 clips played in 10bit 
The 25 fps clips played at 50 Hz and the 30 fps clips played at 60 Hz. No stuttering or any playback issues.
CoreELEC (official): devel-1549511200
COREELEC_DEVICE=“S905”
Before playback:
1920x1080p60hz, 10-bit, YUV444, SDR
25 Hz (mediainfo says all three clips are 25fps)
0. Astra DVB Sample (2160p 420 10bit (BT.709) 25fps 19mbit)
Kodi: 3840x2160p50hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
- Samsung Fashion Show Milan 4K Demo (2160p 420 10bit (BT.709) 25fps 61mbit)
Kodi: 3840x2160p50hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
- LG New York HDR UHD 4K Demo (2160p 420 10bit (BT.2020) 25fps 51mb)
Kodi: 3840x2160p50hz 10-bit YUV420 HDR10
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
30 Hz (mediainfo says all four clips are 30fps)
- Samsung The Quiet Czech 4K Demo (2160p 420 10bit (BR.709) 30fps 51mbit)
Kodi: 3840x2160p60hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 60 Hz YCbCr420 30bit
- Samsung Dive To The New World 2160p Demo (2160p 420 10bit (BT.709) 30fps 51mb)
Kodi: 3840x2160p60hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 59 Hz YCbCr420 30bit
- Samsung Iceland 4K Demo (2160p 420 10bit (BT.709) 30fps 51mbit)
Kodi: 3840x2160p60hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 59 Hz YCbCr420 30bit
- Samsung HDR Picture Quality 4K Demo (2160p 420 10bit (BT.2020) 30fps 50mbit)
Kodi: 3840x2160p60hz 10-bit YUV420 HDR
Receiver: HDMI 1 4K(3840x2160) 59 Hz YCbCr420 30bit
50 Hz
- Astra SES UHD 4K Demo (2160p 420 10bit (BT.709) 50fps 24mbit)
Kodi: 3840x2160p50hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
- LG La Boheme 4K Demo (2160p 420 10bit (BT.709) 50fps 62mbit)
Kodi: 3840x2160p50hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
- TravelXP 4K HDR HLG Demo (2160p 420 10bit (BT.2020 HLG) 50fps 20mbit)
Kodi: 3840x2160p50hz 10-bit YUV420 SDR
Receiver: HDMI 1 4K(3840x2160) 50 Hz YCbCr420 30bit
Regarding clip 9, I suspect HLG is not supported as Kodi says EOTF is SDR which didn’t trigger the HDR logo on my TV.