Mine does that too. But after 3 seconds the USB stick ends up reading and away I go with my tunes. For beginners just plop a bunch of mp3s in the main area of the usb drive. Once you get folders and albums like that gets a bit more finicky for some.
I have also gotten my old 30 gig iPod classic to run on my Mirage's stereo pretty simply with the iPod cord. And all my cellphones from Android 2.0 up have been readable in my Mirage. I think how your folders are arranged makes a huge difference.
I had a 2019 Hyundai Santa Fe rental a few years ago and I had more trouble getting my usb stick to work. I wasn't used to that stereo of course.
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View my fuel log 2014 Mirage ES 1.2 manual: 42.2 mpg (US) ... 17.9 km/L ... 5.6 L/100 km ... 50.7 mpg (Imp)