There probably should be a sticky message for this topic since it’s caused a lot of confusion.
As far as I know, there are two options for you.
You can still go into the ESC menu and go to assistance and turn ATC back on there. You just can’t turn it on in the pull-down menu in-flight, which was a bummer.
Your other option is to disable the “disable” feature altogether by changing “disable_assistances” in the flight_model.cfg file. If you never had issues with the assistance settings impacting your flights (I never seemed to have this issue) this is the best option. You will need to do this each time you update the plane I think. This is currently what I do.
Change the 1 to a 0 here:
