sad to read that, i think most if not all problem like that depend of windows settings, something not default/standard, but microsoft said nothing about it untill you got the problem, if you install another xbox soft - xbox app, so msy be will not overkill relogining there, then watch windows settings like firewall, i have disabled uac for death, and need to back opportunity to start simulator as not admin only for buy something in marketplace, or i had to back uac by same reason for download msfs year ago, any way watch your windows settings, something can prevent to work with msfs by normal way
good luck