Well I know this is not a big problem, but it always happened and make me feel uncomfortable, especially when I can enjoy my favourite online vehicles in story mode but I can't custom them properly. I changed my trainer from SNT to ENT but it keeps same. so I think it's not the trainer's problem, there must be some bugs in the game that interrupt the functions,  this happened in Schafter V12, Schafter LWB and rapid gt classics, or sometimes in IVPack. in custom shop there are only four custom options for it. anyone has the same problem like me?