If an older
Ion, I have seen where some brands of thumb drives cannot be read by the top drive slot. I have no luck with HP or Microcenter drives as example, but am lucky with Sandisk and Kingston brand.
You can also try a rear drive slot, which I have no issues with, but now-a-days I just use brands I know work.
I think this is a mother board issue, but found a work-around with the different brands.