It seems that @orangebucket is correct. I removed the device from the hub and changed the hub to channel 11. And I lost the ability to re-pair it.
Then I changed the hub to channel 21, And couldn’t add it. And finally put it back the the original channel 24. And paired first time with no issues.
I’ll continue my plan to move all ZigBee devises onto my new HH2. And then I’ll try both v3s on channel 24, as a group. Hopefully it will work. Worst case I’ll lose the arrival sensors which is a shame. I have one in each of the cars. So if the car is robbed it will notify me.