With 6.x, all the information of media section in the gui is pulled up from EMM.
How many media servers do you have?
Did you get any error when running nbpushdata?
run nbemmcmd -listhosts -verbose
nbemmcmd -getemmserver
nbemmcmd -listmedia -all
You should most likely see errors in above commands also.
Paste those errors here and may be the experts this community will have some solution