Desk USB choosy ?

I've not had a problem with any USB media plugged directly into a desk.

Have you checked that the USB drive is correctly formatted? (Presumably a FAT32 partition is the most obvious option...)

I have not had any issues with using them on my Ion either. I have the one that came with the board and another older 1GB drive (memorex I believe) that work. And I've used about 6 or so various brands (a couple with no names on them) from designers  and never had issues with them.

The console can use any writable USB stick that registers itself as a single "USB Mass Storage Device" and is formatted either FAT16, FAT32 (recommended) or NTFS. It cannot have any features that require any applications to run, because Eos will not run them.

The original thread seemed to be that the USB sticks in question died.

Unfortunately flash memory tends to fail without any kind of warning - one day it's absolutely fine, the next it's a brick. I've had that happen to me a few times with various brands.

However, several manufacturers of USB sticks have put very strange formatting regimes on them, apparently in a misguided attempt to 'differentiate' their products.

For example the SanDisk "U3" USB sticks called themselves a CD-ROM drive and a Mass Storage. (I believe SanDisk have now stopped shipping U3, though they do seem to have put something else there instead on some models)
Some other USB sticks register themselves as a floppy drive plus mass storage etc.

Unfortunately, the 'differentiation' they've acheived is to make them unusable until you've stripped it off - you can't just format it to make it behave.

Thankfully U3 did come with a removal utility on it, though not all USB sticks with such 'useful' utilities on them can have them removed though, so I would avoid USB sticks that claim any additional 'features'.