Do you have the same issue if you follow the OP’s steps to reproduce it?
Yes
Provide extra information to complete the original description of the issue:
Using a flight number with 3 digits and a zero in the middle, like 101, 202, 303. To have the number transformed into stars, I have to exit/enter the Customization window a couple of times (switching from 1 airplane to another a couple of time for example) before seeing the issue. If I use a number with more digits or for example “203” so far I cannot reproduce it but it really looks a random issue. I don’t know what is the logic that triggers the switch between the number and the stars. Maybe some additional variations in the number format are also affected. Only a dev with access to a debug log file could identify the logic behind this and so the root cause.
If relevant, provide additional screenshots/video:
Maybe that issue is linked to another one where flight number is not saved: