I have a new Y running 2020.28.6. Tried putting some music on a 128Gb flash drive in a Music folder and a separate TeslaCam folder. This morning I tried to listen for the first time and found NO USB icon. Read this forum. Went down to the car and mysteriously the USB icon was there and music played just fine. No software change during the day today. So I'm thinking maybe an intermittent, bad connection issue??
I have just (with difficulty) partitioned the USB flash drive into two partitions. One for TeslaCam and one for Music. Hoping that will work, but still suspicious Tesla has some wiring or hub issues or a software bug. Will keep you posted.