I don't know if this will help anyone, but I am experiencing this same symptom.
I'm running OPNsense 25.1.8_1 configured for HA and KEA on my secondary node fails to start. After reading patient0's comment I went looking at the KEA config of my secondary node and what I found was that the KEA control agent on my secondary node had the IP address of my primary node.
I reset the IP address to the secondary node's IP and KEA started normally. When I checked the configuration of the secondary node later (after HA sync) the IP address was reset to the primary node's IP.
Is there maybe an issue with the HA sync that's overwriting the control agent IP address?
I'm running OPNsense 25.1.8_1 configured for HA and KEA on my secondary node fails to start. After reading patient0's comment I went looking at the KEA config of my secondary node and what I found was that the KEA control agent on my secondary node had the IP address of my primary node.
I reset the IP address to the secondary node's IP and KEA started normally. When I checked the configuration of the secondary node later (after HA sync) the IP address was reset to the primary node's IP.
Is there maybe an issue with the HA sync that's overwriting the control agent IP address?