InDesign Gradient export issue

If we're talking in CMYK terms, I'd bet that your lower-quality result is coming from reducing the number of "shades" you can reproduce for newsprint Cyan as you reduce the resolution with your "smallest size" settings. For newsprint, you're looking at a highlight dot — the lightest shade you can reproduce laying key color blacK ink down on a high-speed newspaper web press — on the order of 10-12%. Cyan's highlight dot would likely be significantly higher. At smaller-size/lower resolution, your color settings are faithfully reporting that your Cyan build is dropping out at low percentages and low resolution until the Magenta and/or key color blacK picks up the slack for your light Cyan percentage across the gradient build.

With a system and display using newsprint color settings/calibrated screen to display how your work will reproduce on press, Your screen is telling you that at low resolution you're on the verge of a world of hurt.

If we're talking exclusively in RGB terms, your light Cyan specification from what I suspect is your print-first workflow isn't translating well into your Blue build onscreen with RGB, and again the gradient at low resolution isn't picking up until your gradient gains its Red and Green components to darken/muddy it up.

In either case, you're going to have to bump up the Cyan build and/or dial in a little more in other color builds in your CMYK gradient — or bump up the resolution to account for more "shades" — to get the result you're looking for onscreen ... and in your screen captures. And I can report this as your problem/solution from unfortunate prior experience.

Hope this helps,

Randy