Likely for the same reason I have $130 in limbo. The Market is not an obvious choice from the wallet for new people when you try to convert to steem power.

I found out how to do it the fast way with the market OR bittrex only recently.

https://steemit.com/powerup/@dwinblood/how-to-convert-steem-dollars-to-steem-and-then-to-more-steem-power-if-you-want