This is not a bug, and it does make sense that it there would be a conflict when using Custom AI drivers. I'm making the post to let people know about this current functionality. Several months ago I made a thread trying to race the GT1s, GroupCs and DPi classes at Daytona to see who would win, but only two of the classes would show up at a time. When choosing different classes this wouldn't happen. At the time some of the players and Reiza staff guessed that the custom liveries were causing the problem - we left it there since I indeed was modding the game, you could expect some things to not work as expected. But just today I confirmed it. It's not the custom liveries. It's the Custom AI Driver profiles. I've never made one and I'm not sure how they work - I think they change not just the name of the drivers and their attributes, but also the make up of the grid itself - how many cars, how many liveries (I think). Well it seems this functionality does conflict with the game when making a multi-class race. If a class has a certain number of drivers with liveries attached to them through the custom AI functionality, it forces the game to... prioritize that class? Or if two classes have Custom AI, then the two conflict with each other and only one might show up. The results can be strange. In some tests it was GT1, GT3, and GTE - with only the GT1 having custom AI, and when the race loaded, only the GT1 class showed up, and my sole GT3 car. Honestly I'm amazed the game didn't crash when having to figure out which cars would show up. Using the Edit Grid functionality, where you choose how many cars in each class show up, is also over-powered by the Custom AI grid. But I tested it, and when you remove the custom AI .xml files, the multi-class grid shows up as expected. So when wanting to set up a multi-class grid, it might be best to remove the custom AI .xml files.
