the dim zones are not wired correctly
the dim zone is broken in the PHD
the fixtures were not programmed to dim to off
Ensure that the fixtures are wired over to purple correctly
Check that the circuit makes it to the first fixture from PHD
Check voltage at the 0-10 controller on the PHD, seeing 1.3V at 10% and 9.7V at 100%, so lights SHOULD be dimming, as they do elsewhere onsite.