Sometimes songs will not even show up in the listings (which i believe is a jreceiver bug)
It's probably just
this old problem, unrelated to the encoding rate, and which is not a bug in the jreceiver software (it's jreceiver working around a bug in the player software). Now, on to your other problem...
what normally happens is that the rio will see the song on its display, but then when i try to play it .. it will just sit there and blink at me.
That might possibly be a problem with the files themselves. Although
this link is related to a different product, the solution might be the same. Check and see.