commission failed with MAAS 3.1 when BMC has multiple channels but the first channel is disabled

One of UA customer can not commission a machine successfully with MAAS 3.1.

The machine has a BMC with 3 LAN channels(3 ports), but only 1 port/channel is enabled(not the first one).

30-maas-01-bmc-config logs are
.....
Unknown section `Lan6_Conf', perhaps another category must be specified (see --category)
Unknown section `Lan6_Conf', perhaps another category must be specified (see --category)
Unknown section `Lan6_Conf', perhaps another category must be specified (see --category)
Unknown section `Lan6_Conf', perhaps another category must be specified (see --category)
.....
ERROR: Unable to determine BMC IP address!
NFO: Loading IPMI kernel modules...
INFO: Checking for HP Moonshot...
INFO: Checking for IPMI...
INFO: IPMI detected!
INFO: Reading current IPMI BMC values...
INFO: Configuring IPMI Lan_Channel...
INFO: Configuring IPMI Lan_Channel_Auth...
INFO: Lan_Channel_Auth settings unavailable!
INFO: Configuring IPMI cipher suite ids...
INFO: Gathering supported cipher suites and current configuration...
INFO: BMC supports the following ciphers - [1, 2, 3, 6, 7, 8, 11, 12, 15, 16, 17]
INFO: Current cipher suite configuration - XXXXXXXXXXXXXXX
INFO: New cipher suite configuration - XXXXXXXXXXXXXXX
INFO: MAAS will use IPMI cipher suite id "17" for BMC communication
WARNING: No K_g BMC key found or configured, communication with BMC will not use a session key!
INFO: Configuring IPMI Serial_Channel...
INFO: Serial_Channel settings unavailable!
INFO: Configuring IPMI SOL_Conf...
INFO: Found existing IPMI user "admin01"!
INFO: Configuring IPMI BMC user "admin01"...
INFO: IPMI user number - User2
INFO: IPMI user privilege level - Administrator
INFO: IPMI Version - LAN_2_0
INFO: IPMI boot type - efi
NFO: Attempting to enable preconfigured static IP on BMC...
INFO: Reading current IPMI BMC values...
INFO: Reading current IPMI BMC values...
INFO: Reading current IPMI BMC values...
INFO: Attempting to enable DHCP on BMC...
INFO: Reading current IPMI BMC values...
INFO: Reading current IPMI BMC values...
......

ii maas-cli 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS client and command-line interface
ii maas-common 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS server common files
ii maas-proxy 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS Caching Proxy
ii maas-region-api 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all Region controller API service for MAAS
ii maas-region-controller 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all Region Controller for MAAS
ii python3-django-maas 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS server Django web framework (Python 3)
ii python3-maas-client 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS python API client (Python 3)
ii python3-maas-provisioningserver 1:3.1.0-10901-g.f1f8f1505-0ubuntu1~20.04.1 all MAAS server provisioning libraries (Python 3)

power configuration is as below:
- power type: IPMI
- Power driver: LAN_2+0[IPMI 2.0]
- Power boot type: automatic
- IP address: 10.x.x.x
- Power user: maasdeploy
- power password: xxxx
- k_g BMC key: empty
- cipher suite ID: 3- HMAC-SHA1::HMAC-SHA1-96::AES-CBC-128
- Privilege level: operator
- power mac A4:BF:01:AB:CD:EC

I ask customer to dump bmc-config via 'bmc-config -h <ipmi-ip> -p <ipmi-password> -u <ipmi-user> --checkout'
PFA bmc_config_channels-clean

From bmc_config_channels-clean we can see that there is only one Lan_conf section. So bmc-config can not recognize the third channel/port where a static IP configured onto. bmc-config only recognize/grab information from the first channel/port of A BMC.
"
Section Lan_Conf
 IP_Address_Source Use_DHCP
 IP_Address 0.0.0.0
 MAC_Address A4:BF:01:AB:CD:EA
 Subnet_Mask 0.0.0.0
 Default_Gateway_IP_Address 0.0.0.0
 Default_Gateway_MAC_Address 00:00:00:00:00:00
 Backup_Gateway_IP_Address 0.0.0.0
 Backup_Gateway_MAC_Address 00:00:00:00:00:00
EndSection
"

We believe that why 30-maas-01-bmc-config complain "ERROR: Unable to determine BMC IP address"