Based on recommendations I read here, when I took delivery of my Model S, I purchased a Micro SD thumb drive and a 32GB Micro SD card.
I filled it with music and it worked flawlessly. I later upgraded the 32GB card to a 64GB card, and that worked just fine as well.
However, immediately after applying the 4.3 firmware update, I noticed that the 64GB drive was no longer showing up under Media.
I tried rebooting the dash and touchscreen, with no luck. I then tried going back to the 32GB card. It mounted immediately and I was able to play music from it. When I went back to the 64GB card, however -- nothing. It doesn't show up. That same card mounts fine on my computer, so the card hasn't gone bad.
I called Tesla, and they hadn't heard about this problem. Has anyone else had a similar experience? Is anyone successfully using a 64GB card with the 4.3 update?