I had the Major update done last Friday (Only been waiting almost 2 months for it!) and sadly it hasn't worked, the SAT NAV is still intermittent on start up, you have to either turn the engine off or hold the power button in to reset it until it works, I have now also lost the ability to receive email/text messages, at least the DAB radio is back! The SAT NAV (When it does work) is out of sync with the map as for the first few miles it prefers to navigate me over grass/railway lines or water rather than the road (I assume that this is a GPS location issue?)
I spoke to the dealership on the Saturday morning and aired my concerns, and as always they did the best that they could - they suggested that I made a video of the issues that I have so that they could send it to Lexus technical department, I did this and they emailed it to them on Tuesday morning, within an hour they had a reply back saying that they are aware of further issues since the last Major Update (July 2018) that is affecting a small amount of cars (unfortunately mine is one of them!) therefore I will have to wait again until it is resolved!!
Not bad for a car that I picked up in March 2018 and I am still without a fully functioning SAT NAV/Multmedia system!
I will keep you posted!