The network-failover disabled is on the default device-group, you don't need to touch that one. Your config looks ok. I've had lots of issues with syncing but usually after an upgrade - they can get stuck without being able to see each other or it may be one way. Deleting the trust, rebooting each F5 and rebuilding the trust usually clears it for a cluster that 'was' working, see if any of following helps (you may have already done some),
- check the failover IPs and config-sync IPs configured on each device
- ping the IPs from each host, check the port lockdown on all HA self-ips
- if any of the peers show disconnected state in Device Mgt - devices or Overview then;
- remove devices from device group, delete peers from trust, reset device trust
- reboot both systems
- setup trust and add to device group and sync,
cheers
Nimbostratus