ASG eating DHCP offers?

We have two SSIDs: One is a guest network that the ASG (2x120 in HA mode, 8.301 with 4xAP10 attached) handles IP addreses for. All is fine in there.

Then we have a wireless network that is bridged to our internal LAN, e.g. Internal WLAN. A Windows Server 2003 is the DHCP server in that subnet.
I can see on that server that devices associated with the internal WLAN send DHCP Discovers and that the Windows Server sends DHCP Offers to the broadcast MAC address.

But when I watch the packets on the device (notebook with Windows XP using Wireshark and filter "port 67 or port 68") I can only see the DHCP Discover packet and no offers at all.

The user symptom is that iOS devices (iPhone, iPad) and also notebooks don't get an IP address and fall back to auto IP.

It seems that the ethernet bridge inside the ASG does not bridge the broadcast packets from the internal LAN over the AP10s to the internal WLAN. That is the expected behaviour though. It did work in the past but seems to have stopped some time in the last few weeks.

In the web admin under Interfaces & Routing -> Bridging there is no bridge defined. I am not sure if that is correct. I guess the "Bridge to AP LAN"-mode creates an implicit bridge?

Any ideas?

-- Paul