Dying Banana-leaf fig?

[Andreas Krull]

Hi,

I bought a healthy looking banana-leaf fig tree 2 month ago for indoors.
Since then it has been loosing 10-15 leafs a day, but, on the other
hand, is growing plenty of new leafs.
It's in a medium-bright environment with average humidity. I put it in a
new soilless mix + fertilizer and water it once a week.
Could the lose of leaves be secondary to bad treatment prior to me
buying it or am I doing something wrong?

Thanks,

Andreas