Deleting/Overwriting savegames doesnt work properly, it doesnt remove all files. When you are testing a new level is very clear, you overwrite the savegame but your truck position remains from the last save and you dont start at your set starting location.
From what I have seen and tested is because the following files do not get deleted!
These files remain
3 being the saveslot number.
Workarond for people on PTS
Delete these 2 files manually