I cannot load any different airport and plane - always the same airport and same aircraft - non ascii windows 10 account name

MODERATOR EDIT: This post was moved into this topic from:
https://forums.flightsimulator.com/t/loading-error-in-sandbox-mode/384625

Hi everyone, I’m having this big problem since I’ve installed the sim (december 2020, premium deluxe edition):
When I want to change the airplane or the airport, it still remains the same. For example, for the first flight, I selected a the A320 at LIBR and it loaded well, the next time, I selected B747 at LIMC, but the simulator still loads the A320 at LIBR. Actually, the only thing that changes is time, from day to night, but everything still remains the same. I tried to uninstall the simulator and re-install it on the Hard disk and on the SSD, I tried to fix the app with app settings and I tried to contact microsoft support(which said “If the problem persist, contact the developers”) but the problem is still there. My PC is new, I bought it in December, so it is not an Hardware problem.
I haven’t installed mods or community packages and I use a mouse, a keyboard and a PS4 controlled with USB connection.

PC specs:
Intel Core i7-10870H CPU @ 2,20GHz
GPU Nvidia Geforce GTX 1650Ti 4GB
256 GB SSD (the sim is installed there)
1TB Hard Disk
16GB RAM

I hope you could help me! Thanks in advance