Video appears to both be Main 10 with different color spaces. (The one that doesn’t work is using 4K HDR colorspace I think while the one that does isn’t)
The only other thing I can think of is the meta tags… I know QT gets angry without “-vtag hvc1” but I’d say you’d need to post logs to see what’s going on.
I’ve only dabble in hevc so blind help here 
Hopefully someone that’s played with this more will jump in
