I partitioned my 3 TB Time Capsule during Lion but now have no access to the partition with Yosemite

I created a 0.5 TB partition on my 3 TB Time Capsule (TC) back when I was running Lion in order to store my 25,000+ tracks of audio. Up through Mavericks I had access to the partition. Now after updating to Yosemite I had access for approximately 2 hours, in which time I moved some new music onto the partition. I left my MBP up and running to finish the transfer and went to bed. The next morning the partition had disappeared and I now cannot find my files. My TC is showing 2.01 TB available and I have not been backing up that long. It makes sense to me that my 126 GB of audio is amongst the 0.99 TB of data used on my TC but how do I access it? ... Please help!!!