Hi!
I faced a similar issue when I bought AppleCare+ while I was in the US, but my Apple account is from Brazil. If you're in a similar situation with accounts from different countries, this might help resolve your problem as well.
Here’s what you can do:
1. On your Apple device, go to Settings > Internet Accounts (MacOS) or Mail > Mail Accounts (iOS) > Add Account. Create a new iCloud account.
2. Log out of your current mail account on the Apple Store by going to Apple Account > Media & Purchases > Sign Out.
3. Open the Apple Store and sign in with your new iCloud account. Try to install an app; it'll ask you to confirm your information. Make sure to set your region to where you purchased your subscription (in my case, the US). Add a valid credit card (I used Wise). The address can be random; for example, you can use a hotel address.
4. Download the Apple Support app and check if you see your covered device. You can also manage your subscription there. If you're using a Mac, simply sign out of the Apple Store and sign in with your new Apple account.
According to the support team, when I purchased AppleCare+, which is not available in Brazil, Apple attempted to link it to a US account that I didn’t have. As a result, my subscription fell into a sort of "limbo" and is not linked to any account. Doing this process you give an account to link to your subscription, and then, be able to manage it.
I hope this helps! Let me know if some steps are unclear.
