The issue that keeps affecting me that doesn't seem to be happening to other people is that on the plan screen, I see no plans. There is a blank table. Weirdly I can select the blank table cell and continue, to get error 012.All i was saying was that there seem to be different fixes depending on whether you are an existing EE customer or not. I collated all the information about what people and EE tech support did to get LTE working. It worked for some but not for all. Don't shoot the messenger. If the registration of the IMIE and EID had worked for you as it did for some people, you would be singing a different tune.
If Level 2 support have registered your IMIE number and it still isn't working then try unpairing and re-pairing as another step as it worked for some people

No one has any idea why. I've emailed tech level 2 and the Watch team screenshots of the issue and they're just treating it like any other case 012.
Part of my frustration is the lackadaisical attitude. If I went to Apple with an issue they fix it same day. If one of my customers comes to me with an issue, I sort it same day. With EE, you just have to wait and wait for departments to communicate. Today, after the three hours of troubleshooting, they just had to call it a day, because it was 6PM and their shift ended.
To me it's simple: I should go to an EE store, pick up a new SIM, level 2 should activate it for me and I should try setting up the Watch on a random number and random temporary plan.
If that works, which it probably would, we can rule out hardware issues.
Then they'd just have to transfer my number over to this new SIM, copy my plan over, and contact billing/credit control to reconfigure all of that, and the job's a goodun'.
This 'scrap everything and start from scratch' approach is apparently not an option, however. No explanation as to why though.
Meanwhile, EE still haven't been able to get roaming running on my account after a whole week. My suspicion is that this is the root cause of my woes, and the reason that no plans are showing: my account is in a weird state of not allowing priced extras (e.g. roaming or a Watch). That suggestion is not being entertained by level 2 unfortunately, who think it is unrelated.
Sigh.