Ah ha! I confess this turned out to be a bit of a head smacker.
Somehow in all my mucking around whenever I switched chroma to ‘on’ it must have been dialed down. And I didn’t help that the source I was using was a little security cam I had lying around that, while color, has pretty low saturation to begin with.
Anyway, the picture is lovely in an aged, glowing, grainy mess kind of way. Thanks all so much for input and the push to keep tinkering…