yesterday
Does anybody know what could be wrong? I don't see Transfer to a work account for one Apple ID account, only Keep as a personal account. I had read https://support.apple.com/en-gb/102159 and checked every option. Once I saw Transfer to a work account, but I was told to update my Mac to the latest OS. After that, I had tried many times without success. It's giving only one option: Keep as a personal account. It wouldn't be a big issue, but the problem is that this Apple ID is used for an APN certificate.
yesterday
I did see somewhere, and I can't find it again, that for that use case you would need to talk to Apple, and they can do something with the account to save it for the APN side of things.
yesterday
You need to call Apple Support and provide them with an alternate Apple ID to reassign your APNS to. They'll want the serial number and expiration date of the cert, the current Apple ID and the ID you're moving it to. They'll also want to verify you're a legitimate employee/representative or your company. Things like proof of employment and copies of business correspondence.
yesterday
The user needs to call Apple.
yesterday
The user is our IT team :) and we have 3 days to migrate that Apple ID. I'll ask to call one of my US colleagues.
yesterday
Shared account I take it, fun. Whoever has access to the password for that account should be able to call and get anything cleared up.
14 hours ago
Thank you @daniel_behan and @AJPinto, solutions seem to be a mix of your advice :) I had a call with an Apple support and they didn't know why that account can't be transferred to a work account and suggested transferring the APN cert to a different account :)