Hi Glenn, I'm not a killer colorist but I have a bit of experience with .cine files as I 'm a lucky Phantom owner.
What exactly do you mean by reading the code ? Getting correct metadata ?
From what I understand, I assume you've tried to change global cine settings in the raw tab settings, but it didn't change a thing, while switching individual clip to custom settings does work.
The only case I know these settings will be ignored is when using the DVR color managed mode. Is this your case here ?
From what I think I've understood by myself, when Resolve is set to color managed mode, linear raw data is automatically mapped into your actual colourspace, bypassing the classic raw tab with specific phantom options, notably the transfer curve selection (rec709, log1 & log2 curves).
While I was trying to set a pipe to color grade .cine files in an HLG colourspace, I've noticed that when color management is ON, the result is quite different to any available curve you can get when in unmanaged mode. And I definitely prefer the rendition I get from the unmanaged mode, with the classic raw tab tools. This color science was probably provided by Vision Research at first, when I suspect the curve being applied by Resolve in managed mode being developed by Blackmagic...
In the case you're in unmanaged mode, then this is an issue, as it has always worked well in any actual or previous Resolve versions...