Ok, now that custom career is fixed, I started a new career and noticed in iracing my name is included in the ai roster, so if I start the race there is a duplicate of me with a 2 suffix on the end. A simple workaround is to delete my ai doppleganger in the iracing ui and carry on as normal. Here's a link to airoster file, season file and custom career config.
Another issue that has crept into this latest release is the AI difficulty - when you change the range to say 40-90, it seems to add a 1 to both values in the config files, and you end up with 41-91 in iracing, strange.