Keithley 2280S-32-6 - front USB "No USB flashdrive found"

Hello,

I would like to ask you to help me diagnose the front USB plug.

The source could not detect any USB flashdrives.  I used variants 2 GB in FAT, 2 GB in FAT32, 4 GB in FAT32. If I click on Menu/Data Buffers/Export to USB, I get "No USB flashdrive found."

When I plug the flashdrives into the PC, their LEDs light up. When I plug them to the source, the LED does not light up.

I think, this is a USB failure, but I may have missed something.