Read the written tutorials instruction #7:
you will also need to add the stage 6 parts to the vehicle(s) you have added or they will disappear when going back to 2.6.0 to play.
Do the following:
Ctrl + F and search "cues": make the bracket open so it will look like the following:
"cues": [
In here, it's as simple as copy pasting the contents of the text document representivie of your car(s) you have added from the Stage6Parts folder, if you have added all new 2.6 cars then simply open the document named "ALL" and paste.
From your nsb file, it will be look like the following (edit the car name & S6 quantity that you like to add):
"cues": [
{
"esnn": 0,
"esut": "ENGINE",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "TURBO",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "INTAKE",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "NITROUS",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "BODY",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "TYRES",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{
"esnn": 0,
"esut": "TRANSMISSION",
"esdb": "Pagani_ZondaBarchetta_2018"
},
5,
{