I'm on Windows 11.
I read your instructions previously. They are easy to understand and follow.
They indicate “Main Menu” > “Missions” > “Challenges”. But my FS4 only has a "Challenges" item on the main screen. There is no "Missions" item on the main screen (see the screenshot, above). I Googled images of the FS4 menu screen, and they show "Missions" on the main screen. It's confusing.
When I go into the "Challenges" item it shows the flights that are in the custom_missions.tmc file, but my custom flight in custom_missions_user.tmc is not displayed.