Sometimes LogicalSwitch cannot be created when adding new L2GW Node to Open vSwitch HWVTEP Emulator

Issue:
After added a new L2GW Node to Open vSwitch HWVTEP Emulator in L2GW HA Cluster, sometimes LogicalSwitch cannot be created in the new node.
Frequency: unclear

Environment details:
OpenStack Version：stable/ocata
ODL Version：Carbon-FR + patch
patch: https://git.opendaylight.org/gerrit/#/c/56773/
https://git.opendaylight.org/gerrit/#/c/56710/
https://git.opendaylight.org/gerrit/#/c/58787/
https://git.opendaylight.org/gerrit/#/c/59598/
HWVTEP: Open vSwitch 2.6.1 HWVTEP Emulator
: HA Cluster

LOG and Detail info:
Please refer to the files attached.
There are three folders. Two of them are OVS info of two l2gw node. The rest one are ODL log and info.