In STEAM go to C:\Users\username\AppData\Roaming\Microsoft Flight Simulator and delete the file content.xml. Restart the sim. The sim will create a fresh xml.
(Assuming all your W10 and Store apps are updated)
Let me know.
Did you update Microsoft Store?
How to Install Microsoft Store updates
Press START and select Microsoft Store
In the top right-hand side corner of the Microsoft Store app, click on the Arrow icon or the three-dot menu > Downloads and updates. Then click Get updates > Update all
Note: You can turn on automatic updates in the Microsoft Store to make sure you won’t miss future updates.
Select the Start screen, then select Microsoft Store
In Microsoft Store at the upper right, select the account menu (the three dots) and then select Settings.
Under App updates, set Update apps automatically to On
Get into Steam and Verify integrity of the game files (client). When it’s not OK you run the risk of re-installing the game. You can check the status of the cllinet in left upper corner Steam/Check for Steam Client Updates
in advance.