DHCP snooping fails on M4250/M4350

Twice now I have tried to enable DHCP Snooping on Netgear networks and both have failed.

Once with M4250-16XF as core to a star configuration of (6) M4250-10G2XF, all v.13.0.4.16.

Once with M4350-24F4V as core to a star configuration of (7) M4350-48G4XF, all v.14.0.2.23.

DHCP not provided by Netgear, so I wanted to enable snooping to prevent possible rogue DHCP services. 
DHCP Snooping globally enabled on all switches.
DHCP Snooping enabled on the DHCP server port, and all trunk ports (both sides).
Valid DHCP source is connected to the "core", and devices connected to the core get an address.
However, no downstream devices receive an address.

If I move the DHCP server to a downstream switch, then the problem appears in reverse.  Obviously the trunks are not passing DHCP request messages.  Any suggestions?