HP MSM765 does not DHCP relay after firmware upgrade

We have an HP MSM765 which we recently upgraded to 6.3.0.0-15824 (to address issues with APs dropping off, which appear to have been resolved).

We then had to reconfigure our firewall as prior to the upgrade, traffic was using NAT (so all traffic was coming from the IP of the MSM).  This feature is no longer compatible with the "Extend VSC egress subnet to VSC ingress subnet" option, so traffic now comes from the client IPs.  No problem now the firewall has been reconfigured.

Before we fixed this we disabled the SSID broadcast so the network was hidden (for testing).  Once we had everything working, we enabled the broadcast (and made no other changes).  Since then, clients connected to the default VSC (for guests) do not receive IP addresses by DHCP (by relay from a Windows server).  Clients connected to the private VSC work fine.

Disabling the broadcast does not fix the problem.  If we restore the config back to how it was, this works fine again (with the SSID disabled) but as soon as we enable broadcast the problem comes back.

Looking through config backups made before and after the change, the only differences are as follows:

On the working config:

  <DHCP-SERVER-REQUEST-LISTEN>
    dhcp-request-listen-lan = ENABLED
    dhcp-request-listen-tunneled-ac = ENABLED

  <MONITOR-PROCESS-LIST>
    .
    .
    dhcp-relay = ENABLED

On the broken config:

  <DHCP-SERVER-REQUEST-LISTEN>
    dhcp-request-listen-lan = DISABLED
    dhcp-request-listen-tunneled-ac = DISABLED

  <MONITOR-PROCESS-LIST>
    .
    .
    dhcp-relay = DISABLED

Is it possible to simply change these settings in the command line, on the new firmware?  If so, how do we go about it?

Thanks in advance for any advice.