Thanks for the reply LexBob! The dealer told me that the 12.1 update was out, but not released. Sometimes I can get to the 12.1 page on Lexus.com, but most of the time when inquiring about the latest version, I am directed to the 11.1 page. It's possible that he could be correct on this one.
I had a 2010 ES350 which I traded in. Before I decided to sell it I checked at a nearby dealership and confirmed the thumb drive with version 12.1 was in stock ($169). It was released on October of this year. I've seen on another Lexus forum posts by owners of various models, including ES350's who have had 12.1 installed. I hope you are able to get some resolution on this.