Sedirea japonica dropping green leaves

[Burgos]

Hello all!

I bought a sedirea japonica last winter and it hasn't done much since. It started putting out new leaves in April. They are almost fully developed now.

The problem is that it has been dropping leaves ever since I got it. It lost 2 one day and has gone from having 5 to having only two and the developing one.

I wonder what is causing this because the plant looks green, healthy and the leaves that drop are green with no signs of rot. They just break at the joint between leaf and stem.

Maybe I should check the roots out. I water it every three days or so and humidity is 60-80%. No sunlight, but abundant east light. Outdoors temps 15-25°C.

Any ideas and help are welcome.