I am to understand you might have the same problem of not seeing your Prime's files from your PC when connected? Well, I discovered from another forum, with someone answering another unrelated thread.
Now, I got my files back, or that I could see them now, and so I could transfer, delete, move etc.
1- Click on your SYSTEM icon
2- Click on the STORAGE icon on the left column
3- Now, go and click on that three tiny stacked squares on the top most right hand corner
4- Tap USB COMPUTER CONNECTION
5- You are then presented with two options. For some reason, when I upgraded to Jellybean, the system reset it to such, as I have never touch this in my life, let alone knew about it but...
6- Check the MEDIA DEVICE (MTP) instead of CAMERA (PTP) that it was currently set
7- Now, if you connect your tab to your PC and open Windows File, you should be able to see your your TF201's file folders and all included files like you used to. I hope that would work for you too! Good luck!
Let me know if that did help then? My e-address is email@example.com