Hi - I had a Soul and now a Seltos... My experience in both is that it takes about 15-20 seconds maybe for it to read the USB after starting, and you should be able to play, thereafter, music instantly at any time the car is on. I use a Sandisk Ultra 128GB drive have about 60GB music also. It has worked flawlessly. I'm sorry you're having this problem....
(Looks like currently out of stock at Amazon currently.)
(Looks like currently out of stock at Amazon currently.)

Amazon.com: SanDisk Ultra Fit 128GB USB 3.0 Flash Drive - SDCZ43-128G-GAM46 : Electronics
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