That is major ordeal.
Have any of you tried creating a new Xbox profile (gamertag) and logging into the sim using that gamertag, which will create a new save file for that new profile?
From there try setting up the Hotas settings as you like and see if they will save. If they do, then we know the issue is with your save file and not the sim itself (the sim probably corrupted your save file, so the issue lies within the sim, but I think you understand where I’m going with this.)
If someone could/would do this, it may provide data to help the developers look for a cause to the problem.