Hotlapping (on West Coast)

The hotlapping tool is very finicky, and I am having a lot of trouble with it on the race track in West Coast USA. I don't know why it's doing this, but essentially, at one certain section of the track, if I press 'Add checkpoint' (which I have to, because it's a turn), it does an animation slightly different to whenever I place any other checkpoint, however this checkpoint causes the AI to completely stop, reverse, and end up going in circles or crashing into each other for no known reason. I have tried this over and over again with the exact same outcomes, so I am lost.

Also, is there any way to move and edit the position/time of set markers in the World Editor? That would also be quite helpful to know.

Any help would be appreciated very much, and I am going to submit a suggestion that all vanilla maps should come with pre-set hotlaps (race paths for the AI) because that would make racing a lot easier.

Thanks again