Just wondering if anyone has used the eSIM Quick Transfer on One recently and had issues or not?

Each time I'm getting to the activating stage but then dumped to "Unable to Transfer Phone Number; Your phone number could not be transferred to this iPhone. You can try again or contact One NZ for assistance."

Tried contacting One NZ, but after 40 minutes I got absolutely nowhere, worse than my last trip to the dentist, and even after insisting that they check to see if they can see issues from their end (i.e. check the logs), they kept going on about QR codes. I literally had to point the guy to One's own website. They left it as "well maybe don't use that and just delete and add the QR code", but I'm also worried that whatever is causing the eSIM transfer to fail to activate, might cause readding the SIM as a brand new one to fail to activate as well.

The only 'quirk' I can think of is that I know I'm served by a RCG tower, but surely in this day that shouldn't cause a SIM to not activate right?