My work vehicle has no antenna but it is equipped with a stock Android Auto radio. I loaded an USB pen with several folders of my personal music library and some were accessible while others weren't.

My library is composed of mp3, flac and ogg files. I discounted the ogg files immediately as it is very rare to find an equipment that reads the extension.

The thumb drive worked flawlessly from more than a week, after which I decided to bring it home and load more music. It stopped working. No files were recognised. The radio defaulted to Bluetooth connection. My first idea was that the drive itself had burned but at home again it connects and reads fine on my computer.

I have no errors while transferring files. I have not exceeded the thumb drive capacity. I noticed the radio creates a folder in the drive, so it is finding it but ignoring the files.

Another thing that came to mind was how I format my folders and files names but that does not make sense as a folder and music that I originally loaded stopped being read.

What can be motivating this?

I don't want to connect my phone to the car in anyway.