Mine is inside under lights still. When it goes outside it goes into full afternoon sun. Mine doesn't drop it's leaves coming inside or out. I have found I get a longer growing seasons up north by keeping it inside when night temps are below 65F. For instance. People keep their trees out in fall until much colder night temps. (The tree can handle the cooler temps than I allow mine to see. )Then bring them into a warm heated house. They drop leaves when many transition them. When I bring mine in, during fall...it hits another growing spurt to be honest.
I would chalk it up to needing more sun outside. Change in atmosphere from inside to out. Causing the foliage to drop. It happens...
Georgia climate, May or June...is it outside full time? Because you want it acclimated fully when you do the repot. I do mine end of June early July. But I'm further up north. Once my night temps level to 65F at night and its acclimated for some on the bench.
Here's my tigerbark. Good species...very forgiving.
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