[DaMacFunkin]

You and @timstephens24 are right. If you set color space to YCbCr 4:2:2 and leave deep color mode to auto, A/V dropouts stop. The issue here is, if you select YCbCr 4:2:2, 4K 24/25/30 etc. is output in 8-bit and this includes HEVC 10-bit/HDR video clips. It can't be a bandwidth problem because 4K 24/25/30 10/12-bit 4:2:2, 8-bit 4:2:2/4:4:4 all have the same data rate of 8.91Gbps.

How can you tell that 4k@24hz 4:2:2 & Deep color Auto is outputting 8 bits?
In this mode if i go into my Denon information it can't detect the bit rate and just displays '---'

If I choose 4k@24hz 4:2:2 & Deep color off my Denon reports 8bit.
If i choose 4k@24hz 4:2:2 & Deep color 10bit My Denon reports '---'
If i choose 4k@24hz 4:4:4 (or Auto) & Deep color Auto My Denon Reports 12bit but as you say, you say you start to get audio drop outs and pops with HD audio.
Very Frustrating, i think we need answers, mirror88 assured me the box could playback 4k 24hz 10bit at 4k 24hz 10bit, as of yet i have seen no verification of this.

I've sorted this (sort of).

Set resolution of Zidoo to 3840x2160@24hz.
Set Deep Color as 10bit (you can choose auto, but it will always be 12bit).
Set Color Space as Auto.
Turn Off set set TV to 24hz mode when 24hz is detected --- this is the problem, i think it is trying to force 23.97 on 24hz or trying to force 24hz on 23.97??
Anyway it is a double negative and needs filing into a proper bug report.
At the moment i am watching 4k@24hz in 10bit 4:4:4 with DTS:X audio confirmed by Denon amp and no real problems.