DRC and info panel do not agree with unconnected

This looks like a problem. What version of kicad are you running? Could you share your project here? (So that others could investigate if this bug persists in other kicad versions than yours.)

Kicad bug reporting:
How to: https://www.kicad.org/help/report-an-issue/
Bug tracker: Bugs : KiCad

If you separate gnd zones you should not have any signal crossing the gab. Otherwise you could create a gab antenna.
(I’m not sure if this applies in your case. It seems something is crossing the gab on b.cu if this is a signal and not a gnd pour it could create a problem.)