HP 6220e not recognised by HP support sites

[Solebanana]

HP Envy 6000 series - 6220e - unable to add it to this report from my products because that's the fault.

Firmware version VASBYTPP2N001.2323A.00

Printer prints OK (usually), visible to HP Smart, visible to Windows 11 (usually), visible to HP print and scan doctor, works from WIndows 10 and Android no issues. However, no HP support site appears to be able to detect it, and cannot add manually with serial number because the sites including this one say it's an invalid serial number (which it isn't). I've looked via Windows at the serial number, I've looked at the label, I've looked at the printed information report, it's definitely, definitely the right serial number. I even tried the printer code instead and it wouldn't recognise that either.

Web services already reset. I can't remove then and re-add them because the printer settings page doesn't have that option on it, just reset which I've already done. Right now it's saying web services status enabled, internet connection not connected, printer connection to HP Smart connected, though earlier it was showing internet connection connected.

The only other thing that might be relevant is that when it wasn't co-operating, at one point I had to add it as PCL (that is, tell Windows it was an older printer) because that was the only way it would work. Microsoft on a remote session struggled with it for an hour to sort out previous printer driver issues and eventually got it working. Because it's done I think three rounds of not being visible to Windows despite being online and visible to HP Smart I'm reluctant to do too much fiddling with it. As it's actually printing at the moment (Paint can see it as an available scanner for example) I'm reluctant to do factory resets etc especially as this appears to be a problem with the HP website, not the printer. If it acts up again I might consider trying to delete it from Windows and reinstall it, but I can't see how this is a printer problem when it's working. It's just the website won't add it to my HP profile.

It isn't something stupid like I have to add a lot of zeroes at the end to make it up to 16 characters, or put HP at the beginning, is it? I'm hoping someone will say, you have to do it like this and then it'll work ... 😕