There are always issues with OW RTW ticketing, it seems. I have never lost luggage on one though and I've done about ten of them. The OP did have an unusual problem because LA is not too accustomed to those tickets.
I have had issues with the SCL-IPC-PPT segments, but they always were resolved for me by AA people at SCL. Those flights are always full in the summer (Chile summer) it seems.