Make sure that the folder name is the same as your .dat file name inside that folderSo i made a copy of MENCS19 so i could keep my 2021 cars away from the 2020 and 2019 cars. The cars are not showing in the opponent manager only the name and the numbers are Ill put a picture below so it could help
For example I have folder 2021_MENCS19 and MENCS19 file inside it renamed as 2021_MENCS19.datMake sure that the folder name is the same as your .dat file name inside that folder