I'm having that same problem that im trying to figure out as wellAero Tow Problem still.
Ok I did what you said above.
1. I renamed Grass Flatland Airport: Grass Flats (Aero Tow)
2. I created a recording with the Decathlon.
Now it says no aero tow available at this airport.
When I am creating an airport to zoom I cannot use the + key. I have to hit zoom and then go back and hit View or file or anything at the top before the screen will zoom.
I also have to go to the top to start recording, The "R" for recording was working and then stopped as did the +.