That's what I have in the switch config; please see the snippet I included in my original post.
The problem is that it's not working. The switch itself seems to be consuming the DHCP requests sent by the clients. Here's a debug trace:
000749: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, rcvd 2
000750: 01:50:33: UDP src=68, dst=67
000751: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, stop process pak for forus packet
000752: 01:50:33: UDP src=68, dst=67
000753: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, rcvd 2
000754: 01:50:33: UDP src=68, dst=67
000755: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, stop process pak for forus packet
000756: 01:50:33: UDP src=68, dst=67
000757: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, rcvd 2
000758: 01:50:33: UDP src=68, dst=67
000759: 01:50:33: IP: s=0.0.0.0 (Vlan86), d=255.255.255.255, len 576, stop process pak for forus packet
000760: 01:50:33: UDP src=68, dst=67