Hi all - hoping the experts here can help me diagnose an issue. I bought a 6' tall fiddle leaf fig 2 months ago and I'm starting to see some branch death that might need some addressing on my part.

Background:
The tree is in the NW corner of my home with windows on two sides. It should be getting adequate, indirect sun. No leaves have dropped, nor has there been any sign yet of issues on the leaves. There was some preexisting browning on a couple lower leaves, but they have not gotten worse. Five new, healthy leaves have grown since purchasing. I don't rotate or move the plant except for emptying the drip tray, and return it to its original orientation.

I water every 10 or so days, when my moisture meter gets to around a 4. I water until it drains through the base (around 1-2 liters) and have added a very small amount of Dynagrow 9-3-6 to start. Plant is possibly somewhat root constrained, as I see some thin roots encircling the top edges of the pot. I'm not sure of the overall condition of the roots, but measurements on the moisture meter lead me to believe it's getting adequate water, though it's possible that the root ball is dense and not drying out well enough. My original plan was to wait and repot next summer.

On to the current issue: the tree had three young branches below the (currently) healthier, longer branches (the latter with active leaf growth). These were 4-6" long and had previously lost all their leaves; it's unknown if the leaves had a natural death or were stripped off. These small branches were alive at purchase, but have since withered, become flexible, and died. I do see new growth peeking out in very early stages on the trunk, but the existing young branches have totally failed.

Is this a sign of a larger problem? Or is this natural for being in a new environment or being stripped of their leaves? The established branches seem healthy enough, but I'm concerned this problem is starting near the base and will move upward.

Any advice is appreciated, thanks.