Ah - that's a different matter.
When you "mount" your SD card, you are showing it as available to the PC, so the PC assigns it a letter.
When you unmount, or close the clockworkmod (or come out of it - is the same as unmounting) the PC cannot now see the old mounted device.
So if you plug your phone in and the SD card is not mounted, then even though the letter is there on the PC - it shows no card - hence the "please insert the sd card" message.
I know in my custom rom on the OSF I can mount & unmount from within the main menu, I do not know if jellyfish offers this - but it prob will, but in either case - the sd card HAS to be mounted for file transfer to & from the PC to the SD card to take place.
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