Mine says both PCs are linked to the Microsoft Store :LOk, I looked up https://account.microsoft.com/devices/content and only my old PC is listed as being linked to the Microsoft Store.
Though the new PC is linked to the same Microsoft Account, along with the old PC.
Not sure how to proceed.
The thing is I can deal with not having the Store on my PC cos out of all my time using Windows 10 for many years I've probably only used the store like 3/4 times. But the small things like calculator and there was this Mail app I used for my emails which was really good and easy to use was essential to me.