Here's the reply from the developers:
'iOS does support 10-bit H264 and H265, but the bitrate there is higher than normal for iOS, so it’s not entirely unsurprising that the decoders had difficulty with it. They could try doing an optimize or re-encode the video, but for now those are probably the only options'
Ok, thanks for bringing the question/problem to the developers.
Im not sure if the footage was 10-bit, it was stores straight to a memory card and not through the HDMI port to a monitor with diskdrive.
I tried to "Optimize and Consolidate" the project, and then saw the clips was converted to 96 Mbps, so I then exported the footage at Extreme 100 Mbps, and then played the clip on my laptop. I still got the artifacts, so i now will try to record on my camera at a bitrate that is lower than 150 MBps, so that LumaFusion will not have any issues with my clips. Hopefully that will resolve all the problems.