I had this problem before with files not visible.
I suspect the USB partition cannot be mounted because the drive capacity is too large.
I was able to use an old 512MB USB stick successfully.
Can you try with a small capacity USB drive - or possibly create a small partition
if you do not have an older USB stick. Hope it works for you.
( I am not from Hantek - just a user - so this is not official advice)
Post time 2020-5-3 21:40:52