I am having the same issue with blank QR code, missing 6 digits. I have tried all of the steps and now updated the unit with firmware 1.2 successfully, I can connect to my WiFi, I can connect to the Helix Stadium XL from my computer using the Helix app and it's fine. I have registered the device online with the serial number on the back into my account on the web site (I see the unit is running 1.2 firmware from the app).
When I turn the unit on and try to log into my Line6 account from the unit, there is still no QR code or 6 digits. The manual login is grayed out but I can click on it and enter my username (also tried email) and password and it fails. I logged onto the site and turned off MFA, changed my password and tried it again and still the same issue.
I am noticing some intermittent issues on their website too- sometimes a HTTP 503 error and sometimes 502 (bad gateway). It seems Line6 servers may be the cause of this???
This is very disappointing after spending a lot of money on something this is DOA. I was so excited to get this and start playing it but it appears it's either a bad unit or some Line6 problem. This is my first experience with Line6 products and so far, not so good. Not impressed...