It migrated without any errors and all I had to do was re-pair all my zigbee devices starting with wired devices from closest to the controller to the furthest and then all the battery devices.
Got it sussed with a hint from EverythingSmartHome’s Lewis
The pairing button on the device(s) will flash then ready to pair, but you have to ignore the single and double pulse and keep holding it (20s or so) until it flashes like mad.
Then it pairs.
No idea why they chose to do it that way, but it worked