I swear I have issues maxing out my 128 gig sd on my Vita, and also on my Android. But I cannot offer proof or explanation. Somehow maxing out my vita crapped out some installed DLC (I'm guessing) and a similar thing with my android, I keep transfering the apps to the SD, and they get automatically put back on the system memory when I try to move more to the SD. (this happens automatically when updating an app on the SD, so I know for sure it wasn't from updating.)