More then seven million people saw the holiday camp entertainer triumph in the show last summer and land a deal with music giant Universal.
But midweek chart predictions released today, based on sales patterns so far this week, indicate she has sold so few copies of her self-titled album that she is outside the top 100.
Her poor placing comes just a matter of weeks after one of the runners-up in the 2012 series, Bo Bruce, saw her album go to number ten in the charts. The other finalist Tyler James managed to get to 47 with his release, which came out in October.
Latest sales figures released by the Official Charts Company suggest that Daft Punk are on track to retain their position at number one for a second week with Random Access Memories.
Leanne, 29, was mentored by Sir Tom Jones during her stint on The Voice and she surprised many by beating the favourite, Bruce, in the final a year ago.
The sales disaster will cause many to wonder about the value of winning the BBC show, which is now in its second series. Ratings have taken a huge tumble for this season and Saturday night's programme - as the battle rounds drew to their conclusion - saw the smallest audience of 2013 when an average of 5.9 million tuned in.
Yet BBC bosses are planning to screen a third series of the show.
TV rival The X Factor, which is screened by ITV, saw its most recent winner James Arthur claim the fifth biggest selling single of 2012 shifting almost 900,000 copies of Impossible in only three weeks.