Tested, All .park scenario cannot type the name after you complete the objective, probably a bug from OpenRTC I guess? (idk, finger cross 🤞)
File name .scX / .sc6 / .SC6 works normal.
*Edit: Try > Redbox tool and > Convert saved game to the scenario for each .park and now I can enter name again, so it's a bit of hand click working but that is what you can do right now