Solved.
I have MSFS2024 installed on the D drive, but the contents of the Microsoft Flight Simulator2024 folder on the (C) drive were corrupted, and even when I reinstalled the main game on the D drive, the corrupted files were carried over, so no matter how many times I tried, the world map never worked properly.
By reinstalling the Microsoft Flight Simulator2024 folder on the C drive, I was able to perform free flights.