@dooglus
Here's the explanation:
Nodes displayed in the graph are transactions and edges are txos (inputs/outputs).
If a txo is unspent, there's no "next" transaction. It implies that unspent outputs don't appear in the graph because an edge needs a source and a target node.

Tip: If you put your mouse over the 2nd and 5th outputs in the "Transaction Details" panel, you'll see that they're marked as unspent.

That being said, this is an issue noted in my todo list and for which I'm still looking for a good solution (in term of UX).